# HG changeset patch # User meillo@marmaro.de # Date 1226682986 -3600 # Node ID e050221efd3884cee749a19ab67d51e1a349f73e # Parent 4fabc8ac55382c4dff65f0f47c30ee52b77bd530 much restructuring again diff -r 4fabc8ac5538 -r e050221efd38 thesis/pieces/old/3-MasqmailProject.tex --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/thesis/pieces/old/3-MasqmailProject.tex Fri Nov 14 18:16:26 2008 +0100 @@ -0,0 +1,218 @@ +\chapter{The \masqmail\ project} + +%TODO: have text by oliver here? + +\section{Purpose of \masqmail} + +\subsection{Target field} +Its original author, Oliver Kurth, sees \masqmail\ so: +\begin{quote} +MasqMail is a mail server designed for hosts that do not have a permanent internet connection eg. a home network or a single host at home. It has special support for connections to different ISPs. It replaces sendmail or other MTAs such as qmail or exim. +\end{quote} + +\masqmail\ is inteded to cover a specific niche: non-permanent internet connection and different \NAME{ISP}s. + +Although it can basically replace other \MTA{}s, it is not generally aimed to do so. The package description of \debian\citeweb{packages.debian:masqmail} states this more clearly by changing the last sentence to: +\begin{quote} +In these cases, MasqMail is a slim replacement for full-blown MTAs such as sendmail, exim, qmail or postfix. +\end{quote} +\masqmail\ is a good replacement ``in these cases'', but not generally, since is lacks features essential for running on mail servers. It is primarily not secure enough for being accessable from untrusted locations. + +The program is best used in home networks, which are non-permanently connected to the internet. \masqmail\ sends mail to local destinations, like users on the same machine and on other machines in the local net, immediately. Email to recipients outside the local net are queued when offline and sent when a online connection gets established. + +Further more does \masqmail\ respect online connections through different \NAME{ISP}s; a common thing for dial-up connections. In particular can different sender addresses be set, dependent on the \NAME{ISP} that is used. This prevents mail to be likely classified as spam. + + + +\subsection{Typical usage} +This section describes situations that make senseful use of \masqmail. + +A home network consisting of some workstations without a server. The network is connected to the internet by dial-up or broadband. Going online is initiated by computers inside the local net. \NAME{IP} addresses change at least once every day. + +Every workstation would be equiped with \masqmail. Mail transfer within the same machine or within the local net works straight forward. Outgoing mail to the internet is sent, to the concerning \NAME{ISP} for relaying, whenever the router goes online. Receiving of mail from outside needs to be done by a mail fetch program, like the \masqmail\ internal \NAME{POP3} client or \name{fetchmail} for example. The configuration for \masqmail\ would be the same on every computer, except the hostname. + +For the same network but having a server, one could have \masqmail\ running on the server and using simple forwarders (see \ref{subsec:relay-only}) to the server on the workstations. This setup does only support mail transfer to the server, but not back to a workstation; also sending mail to another user on the same workstation is not possible. + +A better setup is to run \masqmail\ on every machine %FIXME + + + +\subsection{What makes it special} + +As main advantage, \masqmail\ makes it easy to set up an \MTA\ on workstations or notebooks without the need to do complex configuration or to be an mail server expert. + +Workstations use %FIXME + + +\subsection{Alternatives?} +% http://anfi.homeunix.org/sendmail/dialup10.html + +\section{History} +%TODO: let oliver prove read it! +%FIXME: add references +%FIXME: where does the name come from: masqdialer (guessed) + +The date of the first release (version 0.0.1) is unknown. +The only information available is, that it was packaged for \debian\ at 15\nth\ of September in 1999. +Further releases were made every few weeks or month during 2000, 2001 and 2002. +Development ended in mid-2003 in a hard stop. +The last ordinary release known to me is version 0.2.20, released on 4\nth\ of June in 2003. + +During the time of development, Oliver released 53 versions. +That means a new release in less than every 20 days in average! + +Mentionable are the four \emph{beta} releases of version 0.1.8 (named with the trailing letters `a' to `d') in winter 2000/2001 and the security-fix 0.1.15.1 in 2002. + +One extra release (version 0.2.21) was made by him in November 2005. +This one is only available from the \debian\ pool. +Comparing it to version 0.2.20 shows, that no source code was altered. +Only building documents (like Makefiles) and \debian\ packageing documents were changed. +That leeds to the assumption that this last release was specificly created for the needs of \debian---to fix some errors in the package. + +In May 2000 the minor version number increased to `1'. +Nothing special is mentioned in the documentation about that. +When it increased again to start the 0.2.x releases, Oliver titled them as the ``development branch'' of \masqmail. +At that second time, he started developing the 0.2.x ``development branch'', continuing to work on the 0.1.x series. +His parallel work on both branches lasted for four month, and one additional last release, numbered 0.1.17, one more year later. + + + +\section{Taking \masqmail} + + + + +\section{About \freesw\ projects} + +% http://www.faqs.org/docs/artu/ + +There are several differences between \freesw\ projects and projects about proprietary software. +To understand \freesw\ projects, one needs to understand \freesw\ itself first. + +\subsection{About \freesw} +The term ``Free Software'' was coined by the \name{Free Software Foundation} (short: \NAME{FSF}), founded by Richard~M.\ Stallman (known as ``RMS'') in 1985. +Although various licenses make software free, none of them represents the thinking of \freesw\ like the the \GNU\ \gpl\ (short: \GPL). Its first version was written by Stallman in 1989. +One could say, the \GPL\ catalized the \name{Free Software movement}. + +% http://www.fsf.org/about/what-is-free-software + +After all, the \GPL\ was not the first \freesw\ license used. +The \name{MIT License} (or \name{X Consortium License}) for example is older; published in 1988. +Licenses providing the same rights have been used since long time ago. +But none of them was so often (re)used by other projects---thus gattering less awareness. +Further more was the \GPL\ created to be a \emph{general} license for all kinds of programs, unlike most other licenses written for one particular program. + +\freesw\ gives freedoms to its users. +In contrast to proprietary software restricting the users freedom. +The freedoms (or rights) the user has are stated in the \name{Free Software Definition} of the \NAME{FSF}. Namely these are: +% http://www.gnu.org/philosophy/free-sw.html +% http://www.fsf.org/licensing/essays/free-sw.html +\begin{enumerate} + \item The freedom to run the program, for any purpose (freedom 0). + \item The freedom to study how the program works, and adapt it to your needs (freedom 1). Access to the source code is a precondition for this. + \item The freedom to redistribute copies so you can help your neighbor (freedom 2). + \item The freedom to improve the program, and release your improvements to the public, so that the whole community benefits (freedom 3). Access to the source code is a precondition for this. +\end{enumerate} + + +\subsection{The term ``Open Source''} +\name{Open Source Software} often stands for the same as \freesw. +But there is an essential difference: \name{Open Source} focuses on the availability of source code, while \freesw\ is about freedoms for people. + +\name{Open Source Software} is a subset of \freesw, meaning: All \freesw\ is \name{Open Source}, but there exists \name{Open Source Software} that is not free. + +% http://www.gnu.org/philosophy/open-source-misses-the-point.html +% http://catb.org/~esr/open-source.html + + +\subsection{Development of \freesw} +Having source code available and the right to modify it, encouridges programmers to actually do so. +Their modifications are manifoldly. +Some tailor the software to their needs. +Some add features. +Some do it just for fun. +There are no limitations---whoever wants to, may work on it. + +Since the boom of the internet, \freesw\ typically is developed by an open community of programmers interested in the software. +The process of development is watchable by everyone. + +The other, now less common, method is a more closed group, developing in a ``sealed'' room, but releasing finished versions to the public. + +Eric~S.\ Raymond discusses about these methods, which he named \name{the bazaar} and \name{the cathedral} \cite{catb}. + +The following text will focus on the ``bazaar'' model. + + +\subsection{The role of the community} +\freesw\ projects rise and fall with their community! + +Most \freesw\ programs are developed by a very small group of programmers, often only one person. +But they are used by many people. +In between the programmers and the users, are people located who are a bit of both. +These are the ones that write documentation, find bugs and probably even fix it. +They discuss on mailing lists, bulletin boards and \NAME{IRC} chats. +The program is often spread by their ``advertising''. + +The \emph{community} consists of the actual developers and all users that contribute to the program. +Contribution can be one of the described ways, or others like providing a server for the project website for example. + +\emph{Community} is everyone who is in contact through the project. +Be it on the mailing list, the discussion board, or by telling the developers about a new feature wanted. + +There will hardly be a community if no communication channels are available. +If the development team does not provide them, there is a chance that encouraged users set them up on their own. +But this is rare and the program needs to be very popular. %TODO: maybe include an example here (w3m?) + +Projects without a good community tend to die sooner or later. + + +\subsection{Evolution of a community} +Let us look at the process a community establishes: In most times it's only one who has an idea, in the beginning. +He starts developing. +When others get in contact with the project, there may be some who are so much interested that they start co-developing. +Others report bugs, and some only use the program. + +After some time, one will find a small group of core developers, a larger group of contributers (bugs, patches, documentation) and a very large group of users. +The size ratio of the groups vary by type of project. + +One should have that in mind, when starting a \freesw\ project. + + +\subsection{Creating a strong community} +Building up a good community needs some effort of the main developers. +%TODO: search for documents about this topic + +First communication channels need to be set up, to enable the growth of a community. + +Second, development should be visible by everyone who is interested in it. +Time between work done on the project and its visibility to the public should be kept short. +This makes it interesting for other developers to join. +Developers are the core of a community. + +Third, there is a rule of thumb that should be followed: ``Release early, release often!'' \cite{catb}. +Releases are (more) stable versions, primary for users. +They should be created, frequently. +People will more likely use programs of active projects. + +Fourth, the developers should try to get the users ``in the boat''. +Good communities have a large group of users that do not only receive, but also give something back to the project. +The project leaders should motivate users to contribute. +This unlocks a big work force and gets lot of unexiting work done. + +Fifth, documentation matters. +Good documentation makes it easy for users and developers to start. +And it helps to avoid a lot of unsatisfaction. +Documentation is something that shows quality and that people care about the project. + +And sixth, project leaders should be good souvereigns. +They should try to be fair, to motivate, be visionaires and try to put power and work on many shoulders. + +Not to forget: Every work that was done, every contribution that was made and every idea received needs to be honored in an appropriate way! +Volunteer work lives by acknowledgement of the effort spent. + + + + + +\section{Project infrastructure} + diff -r 4fabc8ac5538 -r e050221efd38 thesis/pieces/old/4-CodeAnalysis.tex --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/thesis/pieces/old/4-CodeAnalysis.tex Fri Nov 14 18:16:26 2008 +0100 @@ -0,0 +1,29 @@ +\chapter{Code analysis} + + +\section{Architecture} +Like its anchestor \sendmail, \masqmail\ is a monolitic program. It consists of only one \emph{setuid root}\footnote{Runs as user root, no matter which user invoked it.}\index{setuid root} binary file, named \path{masqmail}. All functionality is included in it; of course some more comes from dynamic libraries linked. + + + +\subsection{Structure} +The \masqmail\ executable can be called under various names for \name{sendmail-compatibility} reasons. This is commonly organized by creating symbolic links with with different names to the \masqmail\ executable. These are \path{/usr/lib/sendmail} and \path{/usr/sbin/sendmail} because many programs expect a \mta\ to be located there. Further more \sendmail\ provides shortcuts by calling it with a different name instead of supplying command line arguments. The best known of it is \path{mailq}, which is equivilent to calling the \MTA\ with the argument \verb+-bq+. \masqmail\ reacts to the names \path{mailq}, \path{smtpd}, \path{mailrm}, \path{runq}, \path{rmail}, and \path{in.smtpd}. The last four are an addition to \sendmail. Not implemented is the name \path{newaliases} because it is not relevant to \masqmail. To provide the command nonetheless, one may write a shell script located at \path{/usr/bin/newaliases}, that simply invokes \verb+masqmail -bi+. + +%masqmail: mailq, mailrm, runq, rmail, smtpd/in.smtpd +%sendmail: hoststat, mailq, newaliases, purgestat, smtpd + +\masqmail\ is written in the \NAME{C} programming language. The program, as of version 0.2.21, consists of 34 source code and eight header files, containing about 9,000 lines of code\footnote{Measured with \name{sloccount} by David A.\ Wheeler.}. Additionally, it includes a \name{base64} implementation (about 300 lines) and \name{md5} code (about 150 lines). For systems that do not provide \name{libident}, this library is distributed as well (circa 600 lines); an available shared library however has higher precedence in linking. + +The only mandatory dependency is \name{glib}---a cross-platform software utility library, originated in the \NAME{GTK+} project. It provides safer replacements for many standard library functions. (The unsafe \verb+sprintf()+ is one example.) Also it offers handy data containers, easy-to-use implementations of data structures, and much more. + +With \masqmail\ comes the small tool \path{mservdetect}; it helps setting up a configuration that uses the \name{mserver} system to detect the online state. Two other binaries get compiled for testing purposes: \path{readtest} and \path{smtpsend}. All three programms use \masqmail\ source code; they only add a file with a \verb+main()+ function each. + +\masqmail\ does not provide an interface for modules with additional functionality. There exists no add-on or module system. But the code is separated by function to the various source files, and some functional parts can be included or excluded by defining symbols. This means adding some argument (like \verb+--enable-maildir+) to the \verb+configure+ call. Thus the concerning code gets not removed by the preprocessor. + + + + +\section{Code quality} + + +\section{Security} diff -r 4fabc8ac5538 -r e050221efd38 thesis/tex/0-preface.tex --- a/thesis/tex/0-preface.tex Fri Nov 14 18:13:14 2008 +0100 +++ b/thesis/tex/0-preface.tex Fri Nov 14 18:16:26 2008 +0100 @@ -4,7 +4,7 @@ \section*{Preface} %FIXME: write about the motivation to cover this topic -%TODO: eventually have some words of oliver here +%TODO: have text by oliver here? \section*{Audience} diff -r 4fabc8ac5538 -r e050221efd38 thesis/tex/1-Introduction.tex --- a/thesis/tex/1-Introduction.tex Fri Nov 14 18:13:14 2008 +0100 +++ b/thesis/tex/1-Introduction.tex Fri Nov 14 18:16:26 2008 +0100 @@ -1,7 +1,13 @@ \chapter{Introduction} \label{chap:introduction} -\section{History of electronic mail} + + + +\section{Transporting mail} + + +\subsection{History of electronic mail} %TODO: have a quote from Bell Labs about email here Electronic mail\index{electronic mail} (short: \name{email})\citeweb{wikipedia:email} is a basic concept in \unix.\citeweb{unix-mail-intro} On \unix\ machines, a lot of information is distributed by \name{system mail}, which is email sent by the operating system. Beside that, email is the common communication system between humans working on computers. @@ -27,9 +33,8 @@ More information about the history of electronic mail can be found at: \citeweb{email:griffiths}, \citeweb{email:crocker}, \citeweb{email:vleck}, \citeweb{email:akkad}, \citeweb{email:murakami}, and \citeweb{email:tomlinson}. A good starting point for general information on internet history is \citeweb{wikipedia:historyoftheinternet}. %TODO: check the websites which ones are the important ones; remove unnessesary ones +\subsection{Definition of \MTA} - -\section{Transporting mail} %TODO: when was the term ``mail transfer agent'' established? This thesis is about a \name{mail transfer agent} (or \index{mail transport agent|see{mail transfer agent}}\name{mail transport agent}, short \NAME{MTA}): \masqmail. \sendmail\ is one too---the most important one. @@ -67,7 +72,7 @@ -\section{\sendmail} +\subsection{\name{sendmail-compatibility}} \label{sec:sendmail} Allman wrote it to transfer emails between different networks, thus giving \sendmail\ mighty address rewriting abilities. In contrast to its predecessor \name{delivermail}, was \sendmail\ designed to offer greatest flexiblity in configuration; this enabled it to deal with any type of network. @@ -88,3 +93,58 @@ \sendmail\ is not only ported to many platforms, even including \name{Microsoft Windows}, but also it is still the prefered \MTA\ on many systems. For deeper knowledge on \sendmail's history, see \cite{costales97} and \cite{vixie01}. + + + + +\section{The \masqmail\ project} + + +\subsubsection{Target field} +Its original author, Oliver Kurth, sees \masqmail\ so: +\begin{quote} +MasqMail is a mail server designed for hosts that do not have a permanent internet connection eg. a home network or a single host at home. It has special support for connections to different ISPs. It replaces sendmail or other MTAs such as qmail or exim. +\end{quote} + +\masqmail\ is inteded to cover a specific niche: non-permanent internet connection and different \NAME{ISP}s. + +Although it can basically replace other \MTA{}s, it is not generally aimed to do so. The package description of \debian\citeweb{packages.debian:masqmail} states this more clearly by changing the last sentence to: +\begin{quote} +In these cases, MasqMail is a slim replacement for full-blown MTAs such as sendmail, exim, qmail or postfix. +\end{quote} +\masqmail\ is a good replacement ``in these cases'', but not generally, since is lacks features essential for running on mail servers. It is primarily not secure enough for being accessable from untrusted locations. + +The program is best used in home networks, which are non-permanently connected to the internet. \masqmail\ sends mail to local destinations, like users on the same machine and on other machines in the local net, immediately. Email to recipients outside the local net are queued when offline and sent when a online connection gets established. + +Further more does \masqmail\ respect online connections through different \NAME{ISP}s; a common thing for dial-up connections. In particular can different sender addresses be set, dependent on the \NAME{ISP} that is used. This prevents mail to be likely classified as spam. + + + +\subsubsection{Typical usage} +This section describes situations that make senseful use of \masqmail. + +A home network consisting of some workstations without a server. The network is connected to the internet by dial-up or broadband. Going online is initiated by computers inside the local net. \NAME{IP} addresses change at least once every day. + +Every workstation would be equiped with \masqmail. Mail transfer within the same machine or within the local net works straight forward. Outgoing mail to the internet is sent, to the concerning \NAME{ISP} for relaying, whenever the router goes online. Receiving of mail from outside needs to be done by a mail fetch program, like the \masqmail\ internal \NAME{POP3} client or \name{fetchmail} for example. The configuration for \masqmail\ would be the same on every computer, except the hostname. + +For the same network but having a server, one could have \masqmail\ running on the server and using simple forwarders (see \ref{subsec:relay-only}) to the server on the workstations. This setup does only support mail transfer to the server, but not back to a workstation; also sending mail to another user on the same workstation is not possible. + +A better setup is to run \masqmail\ on every machine %FIXME + + + +\subsubsection{What makes it special} + +As main advantage, \masqmail\ makes it easy to set up an \MTA\ on workstations or notebooks without the need to do complex configuration or to be an mail server expert. + +Workstations use %FIXME + + +\subsubsection{Alternatives?} +% http://anfi.homeunix.org/sendmail/dialup10.html + + + +\section{Problems to solve} + + diff -r 4fabc8ac5538 -r e050221efd38 thesis/tex/2-MailTransferAgents.tex --- a/thesis/tex/2-MailTransferAgents.tex Fri Nov 14 18:13:14 2008 +0100 +++ b/thesis/tex/2-MailTransferAgents.tex Fri Nov 14 18:16:26 2008 +0100 @@ -1,7 +1,5 @@ \chapter{Mail transfer agents} -\section{\unix\ \MTA{}s} - After having read about the history of electronic mail and the basics of \mta{}s in the last chapter, this chapter introduces a group of \mta{}s. Among them, the already mentioned \sendmail. The selected group will be delimited against other groups of \MTA{}s, which are described as well. The chosen programs will be presented to the reader in a short overview and with the most important facts. The next chapter will show a comparison of these programs in several disciplines. @@ -14,7 +12,7 @@ Following are groups of \mta{}s that will \emph{not} be regarded further. -\subsection{Relay-only \MTA{}s} +\subsection*{Relay-only \MTA{}s} \label{subsec:relay-only} This is the most simple kind of \MTA. It transfers mail only to defined \name{smart hosts}\footnote{\name{smart host}s are \MTA{}s that receives email and route it to the actual destination}. \name{Relay-only} \MTA{}s do not receive mail from outside the system, and they do not deliver locally. @@ -25,7 +23,7 @@ Examples for that group are: \name{nullmailer}, \name{ssmtp} and \name{esmtp}. -\subsection{Groupware} +\subsection*{Groupware} Normally the term ``groupware'' does not mean one single program, but a suite of programs. They build a framework which is then populated with various modules that provide actual funktionality. Modules for mail transfer, file storage, calendars, resource management, instant messaging, etc., are commonly available. One would use one of these program suites if the main work to do is not mail transfer, but providing integrated communication facilities and team working support for a group of people. The most common scenario are companies. They have \name{groupware} running to provide adequate services for their teams to work efficently. But one may use \name{groupware} on the home server for his family members also. @@ -33,7 +31,7 @@ Examples are: \name{Lotus Notes}, \name{Microsoft Exchange}, \name{OpenGroupware.org} and \name{eGroupWare}. -\subsection{``Real'' \MTA{}s} +\subsection*{``Real'' \MTA{}s} There is a third type of \mta{}s in between the minimalistic \name{relay-only} \MTA{}s and the bloated \name{groupware}. Those programs may be named ``real \MTA{}s'', or ``proper \MTA{}s'', though there is no common name. They are what is meant with the term ``\mta''. Common to them is their focus on transfering email, while being able to act as \name{smart host}. Their variety ranges from ones mostly restricted to mail transfer (\name{qmail}) to others already having interfaces for adding further mail processing modules (\name{postfix})---thus everything in between the other two groups. %FIXME: are postfix and qmail good examples? @@ -42,11 +40,11 @@ -\subsection{Programs to sort out} +\subsection*{Programs to sort out} \name{Mail transfer agent}s can be segmented in various ways, apart from the classification above. Groups of programs wiproperties significantly different from \masqmail\ will be sorted out now. -\subsection{Non-\emph{sendmail-compatible} \MTA{}s} +\subsection*{Non-\emph{sendmail-compatible} \MTA{}s} Due to \sendmail's significance---described in section \ref{sec:sendmail}---compatiblity interfaces for \sendmail\ are of importance for \unix\ \MTA{}s. Being not \emph{sendmail-compatible} does not need to matter for some fields of action, but makes the program ineligible for serving as a general purpose \MTA\ on \unix\ systems. Hence all \MTA{}s not having a \emph{sendmail-compatible} interface or not offering it as a compatibility addon, will not be covered here. @@ -54,7 +52,7 @@ An Examples here is \name{Apache James}. %FIXME: check if correct -\subsection{Non-free software} +\subsection*{Non-free software} Only programs being \freesw\ are regarded, because comparing \freesw\ with proprietary or commercial software is not what typical users of programs like \masqmail\ do. Comparison with those non-free programs may be a point for large \freesw\ projects, trying to step into the business world. Small projects, mostly used by individuals at home, need to be compared against other projects of similar shape. The comparison should be seen from \masqmail's point of view, so non-free software is out of the way. @@ -72,7 +70,7 @@ Following is a small introduction to each of the five programs chosen for comparision. -\subsection{\sendmail} +\subsection*{\sendmail} \label{sec:sendmail} \sendmail\ is the most popular \mta. Since it was one of the first \MTA{}s and was shipped by many vendors of \unix\ systems. @@ -87,7 +85,7 @@ More information can be found on the \sendmail\ homepage \citeweb{sendmail:homepage} and on \citeweb{wikipedia:sendmail} and \citeweb{jdebp}. -\subsection{\name{qmail}} +\subsection*{\name{qmail}} \label{sec:qmail} \name{qmail} is seen by its community as ``a modern SMTP server which makes sendmail obsolete''. It was written by Daniel~J.\ Bernstein starting in 1995. His primary goal was to create a secure \MTA\ to replace the popular, but vulnerable, \sendmail. @@ -98,7 +96,7 @@ The programs homepages are \citeweb{qmail:homepage1} and \citeweb{qmail:homepage2}. Further information about \name{qmail} is available on \citeweb{lifewithqmail}, \citeweb{wikipedia:qmail} and \citeweb{jdebp}. -\subsection{\name{postfix}} +\subsection*{\name{postfix}} \label{sec:postfix} The \name{postfix} project was started in 1999 at \name{IBM research}, then called \name{VMailer} or \name{IBM Secure Mailer}. Wietse Venema's program ``attempts to be fast, easy to administer, and secure. The outside has a definite Sendmail-ish flavor, but the inside is completely different.''\citeweb{postfix:homepage} In fact, \name{postfix} was mainly designed after qmail's architecture to gain security. But in contrast to \name{qmail} it aims much more on being fast and full-featured. @@ -109,7 +107,7 @@ Additional information is available on the program's homepage \citeweb{postfix:homepage}, on \citeweb{jdebp} and \citeweb{wikipedia:postfix}. -\subsection{\name{exim}} +\subsection*{\name{exim}} \label{sec:exim} \name{exim} was started in 1995 by Philip Hazel at the \name{University of Cambridge}. Its age is about the same as \name{qmail}'s, but the architecture is totally different. @@ -122,7 +120,7 @@ One finds \name{exim} on its homepage \citeweb{exim:homepage}. More information about it can be retrieved from \citeweb{wikipedia:exim} and \citeweb{jdebp}. -\subsection{\masqmail} +\subsection*{\masqmail} \label{sec:masqmail} The \masqmail\ program was written by Oliver Kurth, starting in 1999. His aim was to create a small \mta\ which is especially focused on computers with dial-up connections to the internet. \masqmail\ is easy configurable for situations which are rarely solveable with the common \MTA{}s. @@ -185,6 +183,9 @@ masqmail: monolitic +Like its anchestor \sendmail, \masqmail\ is a monolitic program. It consists of only one \emph{setuid root}\footnote{Runs as user root, no matter which user invoked it.}\index{setuid root} binary file, named \path{masqmail}. All functionality is included in it; of course some more comes from dynamic libraries linked. + + exchange: (unknown) @@ -240,126 +241,20 @@ -\section{The future of communication} -\label{chap:future-of-communication} -As globalization proceeds, long distance communication becomes more and more important. This chapter tries to locate trends in communication methods and their impact on the future for communication. The insights gathered from the analysis will be applied to \masqmail, afterwards. -\subsection{Communication methods} -\label{sec:communication-methods} -Today's long distance communication methods are either written or spoken information. And on the other side, they can be classified by the time between responses. -A classification of long distance communication methods is shown in figure %\ref{fig:}. -% slow | | | -% | | letter | days -% | | | -% | | | -% | answering | email | -% | machine | telefax | few seconds -% | | SMS | -% fast | | | -% | telephone | IM | real time -% ----------------------------------------------------- -% response | spoken | written | delivery time +\subsubsection*{masqmail stuff} -% TODO: find reference literature +The \masqmail\ executable can be called under various names for \name{sendmail-compatibility} reasons. This is commonly organized by creating symbolic links with with different names to the \masqmail\ executable. These are \path{/usr/lib/sendmail} and \path{/usr/sbin/sendmail} because many programs expect a \mta\ to be located there. Further more \sendmail\ provides shortcuts by calling it with a different name instead of supplying command line arguments. The best known of it is \path{mailq}, which is equivilent to calling the \MTA\ with the argument \verb+-bq+. \masqmail\ reacts to the names \path{mailq}, \path{smtpd}, \path{mailrm}, \path{runq}, \path{rmail}, and \path{in.smtpd}. The last four are an addition to \sendmail. Not implemented is the name \path{newaliases} because it is not relevant to \masqmail. To provide the command nonetheless, one may write a shell script located at \path{/usr/bin/newaliases}, that simply invokes \verb+masqmail -bi+. -\paragraph{Speed} -Communication gets faster in general. Slow mediums as letters get substituted by electronic mail, which is delivered within seconds. Also communication becomes more transmitted through digital channels. This can be seen at the telephone which's information is now more and more transported in bits over the internet link. Also telefaxes are succeeded by email or are transported within email. Instant messaging can be seen as the written couterpart to the telephone; not to substitute it completely, but to be used if it is more useful for the information to transmit. +%masqmail: mailq, mailrm, runq, rmail, smtpd/in.smtpd +%sendmail: hoststat, mailq, newaliases, purgestat, smtpd -Many of the digital communication methods gained success by beeing cheaper than their counterparts. One example here is instant messaging in contrast to the telephone. As phoning costs fell, it became more popular again. The last years showed, that communication cost degreased dropped generally, caused by the transport through digital channels. And nothing to see, that would make them rise again. +\masqmail\ is written in the \NAME{C} programming language. The program, as of version 0.2.21, consists of 34 source code and eight header files, containing about 9,000 lines of code\footnote{Measured with \name{sloccount} by David A.\ Wheeler.}. Additionally, it includes a \name{base64} implementation (about 300 lines) and \name{md5} code (about 150 lines). For systems that do not provide \name{libident}, this library is distributed as well (circa 600 lines); an available shared library however has higher precedence in linking. -It seems as if in future will be low-cost communication methods available, which will be digitally transmitted. +The only mandatory dependency is \name{glib}---a cross-platform software utility library, originated in the \NAME{GTK+} project. It provides safer replacements for many standard library functions. (The unsafe \verb+sprintf()+ is one example.) Also it offers handy data containers, easy-to-use implementations of data structures, and much more. -\paragraph{Variety} -Regarding the variety of communication methods shows a change, too. Communication systems are more easy to establish today, so more get established. This leads to more methods a person uses. But not only in the amount, also in parallel. For example when two people talk to each other on the phone, one might send a URI\footnote{Uniform Resource Identifier} by email meanwhile, because oral communication is not well suited to exchange such data. Another example for in parallel used communication channels is video chatting. Ony typically sees the other person, talks to it, and additionally has a instant messaging facility for exchanging written information. +With \masqmail\ comes the small tool \path{mservdetect}; it helps setting up a configuration that uses the \name{mserver} system to detect the online state. Two other binaries get compiled for testing purposes: \path{readtest} and \path{smtpsend}. All three programms use \masqmail\ source code; they only add a file with a \verb+main()+ function each. -Parallel usage of different kinds of communication channels will be important in future. The most common combinations are one for spoken and one for written information. But one for dialogs and one for sending documents will be important too. - -\paragraph{Hardware} -Next about the hardware needed for communicating. On the one side stands the telephone, now available as the mobile phone. It provides spoken dialog by calling, spoken messages with the included answering machine and written messages in form of short message service. On the other side stands the letter and its relatives. They need pen and paper, a telefax machine or in most today's cases a computer. They typically send documents, only instant messaging is focused on dialog. - -The last years finally brought the two groups together, with \name{smart phones} being the merging element. Smart phones are computers in the size of mobile phones. They provide both functions, using it as telephones and as computers. - -It matches well the requirements of telephoning and short message service, for which it was designed of course. Also providing being suitable for instant messaging in what is needed additionally to the telephone and short message service. The only problem is the minimal keyboard available to insert text. This also affects writing documents in case of email. It can be done but not very comfortably. Further communication methods include voice and video messages. - -This leaves us with the need for ordinary computers for the field of exchanging documents, and as better input hardware for all written input. - - - -\subsection{Trends for electronic mail} -\label{sec:email-trends} -The previous section stated that electronic mail will still be important in future to complete the communication methods provided by phone and instant messaging. - -But will emailing in future not be the same as emailing now. This will mainly affect how email is transfered. - -\paragraph{Provider oriented emailing} -Today's email structure is heavily dependent on email providers. This means, most people have email addresses from some provider. These can be the provider of their online connection (e.g.\ \NAME{AOL}, \name{T\~Online}), freemail provider (e.g.\ \NAME{GMX}, \name{Yahoo}, \name{Hotmail}) or provider that offer enhanced mail services that one needs to pay for. Outgoing mail is send either with the webmail client of the provider or using \name{mail user agent}s sending it to the provider for relay. Incoming mail is read with the webmail client or retrieved from the provider via \NAME{POP3} or \NAME{IMAP} to the local computer to be read in the \name{mail user agent}. This means all mail sending and receiving work is done by the provider. - -The reason therefor is originated in the time when people used dial-up connections to the internet. A mail server needs to be online to receive email. Sending mail is no problem, but receiving it is hardly possible with an \MTA\ being few time online. Internet service providers had servers running all day long connected to the internet. So they offered email service. - -\paragraph{Provider independence} -Nowadays, dial-up internet access is rare; the majority has broadband internet access paying a flat rate for it. So being online or not does not affect costs anymore, even traffic is unlimited. Today it is possible to have an own mail server running at home. The last technical problem remaining are the changing \NAME{IP} addresses one gets assigned every 24 hours. But this is easily solvable with one of the dynamic \NAME{DNS} services around; they provide the mapping of a fixed domain name to the changing \NAME{IP} addresses. - -Home servers become popular in these days, for central data storage and multi media services. Being assembled of energy efficient elements, power consumption is no big problem anymore. These home servers will replace video recorders and music collections in the near future. It is also realistic that they will manage heating systems and intercoms too. Given the future leads to this direction, it is a logical step to have email and other communication will be provided by the (or one of) the own server aswell. - -After \mta{}s have not been popular for users in the last time, the next years might bring them back to them. Maybe in a few years nearly everyone will have one running at home \dots\ possibly without knowing about it. - -\paragraph{Is email future-safe?} -It seems as if electronic mail or a similar technology has good chances to survive the next decades. This bases on the assumption that it always will be important to send information messages. These can be notes from other people, or notifications from systems (like a broken or full hard drive in the home server, or the coffee machine ran out of coffee beans). Other communication technologies are not as suitable for this kind of messages, as email, short message service, voice mail, and the like. Telephone talks are more focused on dialog and normally interrupt people. These kind of messages should not interrupt people, unless urgent, and they do not need two-way information exchange. The second argument appies to instant messaging too. If only one message is to be send, one does not need instant messaging. Thus, one type of one-way message sending technology will survive. - -Whether email will be the one surviving, or short message service, or another one, does not matter. Probably it will be \name{unified messaging}, which includes all of the other ones in it, anyway. \MTA{}s are a kind of software needed for all of these messaging methods---programs that transfer and receive messages. - -\paragraph{Pushing versus polling} -The retrieval of email is a field that is about to change now. The old way is to fetch email by polling the server that holds the personal mail box. This polling is done in regular intervals, often once every five to thirty minutes. The mail transfer from the mail box to the \name{mail user agent} is initiated from the mail client side. The disadvantage herewith is the delay between mail actually arriving on the server and the user finally having the message on his screen. - -To remove this disadvantage, \name{push email} was invented. Here the server is not polled every few minutes about new mail, but the server pushes new mail directly to the client on arrival. The transfer is initiated by the server. This concept became popular with the smart phones; they were able to do emailing, but the traffic caused by polling the server often was expensive. The concept workes well with mobile phones where the provider knows about the client, but it seems not to be a choice for computers since the provider needs to have some kind of login to push data to the computer. - -The push concept, however could swap over to computers when using a home server and no external provider. A possible scenario is a home server receiving mail from the internet and pushing it to computers and smart phones. The configuration could be done by the user through some simple interface, like one configures his telephone system to have different telephone numbers ring on specified phones. -%FIXME: add reference to push email - -\paragraph{Internet Mail 2000} -Another concept to redesign the electronic mail system, but this time focused on mail transfer is named ``Internet Mail 2000''. It was proposed by Daniel J.\ Bernstein, the creater of \name{qmail}. Similar approaches were independently introduced by others too. - -As main change it makes the sender have the responsibility of mail storage; only a notification about a mail message gets send to the receiver, who can fetch the message then from the sender's server. This is in contrast to the \NAME{SMTP} mail architecture, where mail and the responsibility for it is transfered from the sender to the receiver. - -\name{Mail transfer agent}s are still important in this mail architecture, but in a slightly different way. Their job is not transfering mail anymore---this makes the name missleading---they are used to transport the notifications about new mail to the destinations. This is a quite similar job as they do in the \NAME{SMTP} model. The real transfer of the mail can be done in any way, for example via \NAME{FTP} or \NAME{SCP}. - -%FIXME: add references for IM2000 - - -\section{Market analysis} - -\subsection{\NAME{SWOT} analysis} -%TODO - - - -\subsection{What will be important} -\label{sec:important-for-mtas} -Now that it is explained why email will survive (in some changed but related form), it is time to think about the properties required for \mta{}s in the next years. As the fields and kinds of usage change, the requirement change too. - -Provider independence through running an own mail server at home asks for easy configuration of the \MTA. Providers have specialists to configure the systems, but ordinary people do not. Solutions are either having some home service system for computer configuration established with specialists coming to one's home to set up the systems; like it is already common for problems with the power supply or water supply system. Or configuration needs to be easy and fool-prove, to be done by the owner himself. The latter solution depends on standardized parts that fit together seamlessly. The technology itself must not be a problem itself. Only settings custom to the users environment should be left open for him to set. This of course needs to be doable on a simple configuration interface like a web interface; non-technical educated users should be able to configure the system. - -\sendmail\ and \name{qmail} appear to have bad positions at this point. Their configuration is complex, thus they would need simplification wrappers around them to provide easy configuration. - -The approach of wrappers around the main program to make it look easier to the outside is a good concept in general. %FIXME: add ref -It still lets the specialist do complex and detailed configuration, and also offering a simple configuration interface to novices. Further more is it well suited to provide various wrappers with different user interfaces (e.g.\ a graphical program, a website, a command line program; all of them either in a questionaire style or iteractive). - -When \MTA{}s become popular on home servers and maybe even on workstations and smart phones, then performance will be less important. Providers need \mta{}s that process a large amount of mail in short time. Home servers or workstations however, do not see that much mail; they need to handle tens or hundrets of email messages per hour. Thus performance will probably not be a main requirement for an \MTA\ in the future, if they mainly run on private machines. - -\name{postfix} focuses much on performance, this might not be an important point then. - -New mailing concepts and architectures like push email or \name{Internet Mail 2000} will, if they succeed, require \mta{}s to adopt the new technology. \MTA{}s that are not able to change are going to be sorted out by evolution. Thus it is important to not focus too much on one use case, but to stay flexible. Allman saw this property of \sendmail\ one reason for its huge success (see section \ref{sec:sendmail}). - -Another important requirement for all kinds of software will be security. There is a constant trend going from completely non-secured software from the 70s and 80s over growing security awareness in the 90s to security being a primary goal now. This leads to the conclusion that software security will even more important in the next years. As more clients get connected to the internet and especially more computers are waiting for incoming connections (like an \MTA\ in a home server), there are more possibilities to break into systems. Securing software systems will be done with increasing effort in future. - -``Plug-and-play''-able hardware with preconfigured software running can be expected to become popular. Like someone buys a set-top box to watch Pay-TV today, he might be buying a box acting as mail server in a few years. He plugs the power cable in, inserts his email address in a web interface and selects the clients (workstation computers or smart phones) to which mail should be send and from which mail is accepted to receive. That's all. It would just work then, like everyone expects it from a set-top box today. - -Containing secure and robust software is a pre-requisite for such boxes to make that vision possible. - -It seems as if all widely used \mta{}s provide good security nowadays. \name{qmail}'s architecture, also used in \name{postfix}, is generally seen to be conceptually more secure, however. - -In summary: easy configuration, aswell as the somehow opposed flexibility will be important for future \mta{}s. Also will it be security, but not performance. \MTA{}s might become more commodity software, like web servers already are today, with the purpose to include it in many systems and the need of minimal configuration. - - +\masqmail\ does not provide an interface for modules with additional functionality. There exists no add-on or module system. But the code is separated by function to the various source files, and some functional parts can be included or excluded by defining symbols. This means adding some argument (like \verb+--enable-maildir+) to the \verb+configure+ call. Thus the concerning code gets not removed by the preprocessor. diff -r 4fabc8ac5538 -r e050221efd38 thesis/tex/3-MarketAnalysis.tex --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/thesis/tex/3-MarketAnalysis.tex Fri Nov 14 18:16:26 2008 +0100 @@ -0,0 +1,129 @@ +\chapter{Market analysis} + + +\section{The future of communication} +\label{chap:future-of-communication} +As globalization proceeds, long distance communication becomes more and more important. This chapter tries to locate trends in communication methods and their impact on the future for communication. The insights gathered from the analysis will be applied to \masqmail, afterwards. + + +\subsection{Communication methods} +\label{sec:communication-methods} +Today's long distance communication methods are either written or spoken information. And on the other side, they can be classified by the time between responses. + +A classification of long distance communication methods is shown in figure %\ref{fig:}. +% slow | | | +% | | letter | days +% | | | +% | | | +% | answering | email | +% | machine | telefax | few seconds +% | | SMS | +% fast | | | +% | telephone | IM | real time +% ----------------------------------------------------- +% response | spoken | written | delivery time + +% TODO: find reference literature + +\subsubsection*{Speed} +Communication gets faster in general. Slow mediums as letters get substituted by electronic mail, which is delivered within seconds. Also communication becomes more transmitted through digital channels. This can be seen at the telephone which's information is now more and more transported in bits over the internet link. Also telefaxes are succeeded by email or are transported within email. Instant messaging can be seen as the written couterpart to the telephone; not to substitute it completely, but to be used if it is more useful for the information to transmit. + +Many of the digital communication methods gained success by beeing cheaper than their counterparts. One example here is instant messaging in contrast to the telephone. As phoning costs fell, it became more popular again. The last years showed, that communication cost degreased dropped generally, caused by the transport through digital channels. And nothing to see, that would make them rise again. + +It seems as if in future will be low-cost communication methods available, which will be digitally transmitted. + +\subsubsection*{Variety} +Regarding the variety of communication methods shows a change, too. Communication systems are more easy to establish today, so more get established. This leads to more methods a person uses. But not only in the amount, also in parallel. For example when two people talk to each other on the phone, one might send a URI\footnote{Uniform Resource Identifier} by email meanwhile, because oral communication is not well suited to exchange such data. Another example for in parallel used communication channels is video chatting. Ony typically sees the other person, talks to it, and additionally has a instant messaging facility for exchanging written information. + +Parallel usage of different kinds of communication channels will be important in future. The most common combinations are one for spoken and one for written information. But one for dialogs and one for sending documents will be important too. + +\subsubsection*{Hardware} +Next about the hardware needed for communicating. On the one side stands the telephone, now available as the mobile phone. It provides spoken dialog by calling, spoken messages with the included answering machine and written messages in form of short message service. On the other side stands the letter and its relatives. They need pen and paper, a telefax machine or in most today's cases a computer. They typically send documents, only instant messaging is focused on dialog. + +The last years finally brought the two groups together, with \name{smart phones} being the merging element. Smart phones are computers in the size of mobile phones. They provide both functions, using it as telephones and as computers. + +It matches well the requirements of telephoning and short message service, for which it was designed of course. Also providing being suitable for instant messaging in what is needed additionally to the telephone and short message service. The only problem is the minimal keyboard available to insert text. This also affects writing documents in case of email. It can be done but not very comfortably. Further communication methods include voice and video messages. + +This leaves us with the need for ordinary computers for the field of exchanging documents, and as better input hardware for all written input. + + + +\subsection{Trends for electronic mail} +\label{sec:email-trends} +The previous section stated that electronic mail will still be important in future to complete the communication methods provided by phone and instant messaging. + +But will emailing in future not be the same as emailing now. This will mainly affect how email is transfered. + +\subsubsection*{Provider oriented emailing} +Today's email structure is heavily dependent on email providers. This means, most people have email addresses from some provider. These can be the provider of their online connection (e.g.\ \NAME{AOL}, \name{T\~Online}), freemail provider (e.g.\ \NAME{GMX}, \name{Yahoo}, \name{Hotmail}) or provider that offer enhanced mail services that one needs to pay for. Outgoing mail is send either with the webmail client of the provider or using \name{mail user agent}s sending it to the provider for relay. Incoming mail is read with the webmail client or retrieved from the provider via \NAME{POP3} or \NAME{IMAP} to the local computer to be read in the \name{mail user agent}. This means all mail sending and receiving work is done by the provider. + +The reason therefor is originated in the time when people used dial-up connections to the internet. A mail server needs to be online to receive email. Sending mail is no problem, but receiving it is hardly possible with an \MTA\ being few time online. Internet service providers had servers running all day long connected to the internet. So they offered email service. + +\subsubsection*{Provider independence} +Nowadays, dial-up internet access is rare; the majority has broadband internet access paying a flat rate for it. So being online or not does not affect costs anymore, even traffic is unlimited. Today it is possible to have an own mail server running at home. The last technical problem remaining are the changing \NAME{IP} addresses one gets assigned every 24 hours. But this is easily solvable with one of the dynamic \NAME{DNS} services around; they provide the mapping of a fixed domain name to the changing \NAME{IP} addresses. + +Home servers become popular in these days, for central data storage and multi media services. Being assembled of energy efficient elements, power consumption is no big problem anymore. These home servers will replace video recorders and music collections in the near future. It is also realistic that they will manage heating systems and intercoms too. Given the future leads to this direction, it is a logical step to have email and other communication will be provided by the (or one of) the own server aswell. + +After \mta{}s have not been popular for users in the last time, the next years might bring them back to them. Maybe in a few years nearly everyone will have one running at home \dots\ possibly without knowing about it. + +\subsubsection*{Is email future-safe?} +It seems as if electronic mail or a similar technology has good chances to survive the next decades. This bases on the assumption that it always will be important to send information messages. These can be notes from other people, or notifications from systems (like a broken or full hard drive in the home server, or the coffee machine ran out of coffee beans). Other communication technologies are not as suitable for this kind of messages, as email, short message service, voice mail, and the like. Telephone talks are more focused on dialog and normally interrupt people. These kind of messages should not interrupt people, unless urgent, and they do not need two-way information exchange. The second argument appies to instant messaging too. If only one message is to be send, one does not need instant messaging. Thus, one type of one-way message sending technology will survive. + +Whether email will be the one surviving, or short message service, or another one, does not matter. Probably it will be \name{unified messaging}, which includes all of the other ones in it, anyway. \MTA{}s are a kind of software needed for all of these messaging methods---programs that transfer and receive messages. + +\subsubsection*{Pushing versus polling} +The retrieval of email is a field that is about to change now. The old way is to fetch email by polling the server that holds the personal mail box. This polling is done in regular intervals, often once every five to thirty minutes. The mail transfer from the mail box to the \name{mail user agent} is initiated from the mail client side. The disadvantage herewith is the delay between mail actually arriving on the server and the user finally having the message on his screen. + +To remove this disadvantage, \name{push email} was invented. Here the server is not polled every few minutes about new mail, but the server pushes new mail directly to the client on arrival. The transfer is initiated by the server. This concept became popular with the smart phones; they were able to do emailing, but the traffic caused by polling the server often was expensive. The concept workes well with mobile phones where the provider knows about the client, but it seems not to be a choice for computers since the provider needs to have some kind of login to push data to the computer. + +The push concept, however could swap over to computers when using a home server and no external provider. A possible scenario is a home server receiving mail from the internet and pushing it to computers and smart phones. The configuration could be done by the user through some simple interface, like one configures his telephone system to have different telephone numbers ring on specified phones. +%FIXME: add reference to push email + +\subsubsection*{Internet Mail 2000} +Another concept to redesign the electronic mail system, but this time focused on mail transfer is named ``Internet Mail 2000''. It was proposed by Daniel J.\ Bernstein, the creater of \name{qmail}. Similar approaches were independently introduced by others too. + +As main change it makes the sender have the responsibility of mail storage; only a notification about a mail message gets send to the receiver, who can fetch the message then from the sender's server. This is in contrast to the \NAME{SMTP} mail architecture, where mail and the responsibility for it is transfered from the sender to the receiver. + +\name{Mail transfer agent}s are still important in this mail architecture, but in a slightly different way. Their job is not transfering mail anymore---this makes the name missleading---they are used to transport the notifications about new mail to the destinations. This is a quite similar job as they do in the \NAME{SMTP} model. The real transfer of the mail can be done in any way, for example via \NAME{FTP} or \NAME{SCP}. + +%FIXME: add references for IM2000 + + +\section{Market analysis} + +\subsection{\NAME{SWOT} analysis} +%TODO + + + +\subsection{What will be important} +\label{sec:important-for-mtas} +Now that it is explained why email will survive (in some changed but related form), it is time to think about the properties required for \mta{}s in the next years. As the fields and kinds of usage change, the requirement change too. + +Provider independence through running an own mail server at home asks for easy configuration of the \MTA. Providers have specialists to configure the systems, but ordinary people do not. Solutions are either having some home service system for computer configuration established with specialists coming to one's home to set up the systems; like it is already common for problems with the power supply or water supply system. Or configuration needs to be easy and fool-prove, to be done by the owner himself. The latter solution depends on standardized parts that fit together seamlessly. The technology itself must not be a problem itself. Only settings custom to the users environment should be left open for him to set. This of course needs to be doable on a simple configuration interface like a web interface; non-technical educated users should be able to configure the system. + +\sendmail\ and \name{qmail} appear to have bad positions at this point. Their configuration is complex, thus they would need simplification wrappers around them to provide easy configuration. + +The approach of wrappers around the main program to make it look easier to the outside is a good concept in general. %FIXME: add ref +It still lets the specialist do complex and detailed configuration, and also offering a simple configuration interface to novices. Further more is it well suited to provide various wrappers with different user interfaces (e.g.\ a graphical program, a website, a command line program; all of them either in a questionaire style or iteractive). + +When \MTA{}s become popular on home servers and maybe even on workstations and smart phones, then performance will be less important. Providers need \mta{}s that process a large amount of mail in short time. Home servers or workstations however, do not see that much mail; they need to handle tens or hundrets of email messages per hour. Thus performance will probably not be a main requirement for an \MTA\ in the future, if they mainly run on private machines. + +\name{postfix} focuses much on performance, this might not be an important point then. + +New mailing concepts and architectures like push email or \name{Internet Mail 2000} will, if they succeed, require \mta{}s to adopt the new technology. \MTA{}s that are not able to change are going to be sorted out by evolution. Thus it is important to not focus too much on one use case, but to stay flexible. Allman saw this property of \sendmail\ one reason for its huge success (see section \ref{sec:sendmail}). + +Another important requirement for all kinds of software will be security. There is a constant trend going from completely non-secured software from the 70s and 80s over growing security awareness in the 90s to security being a primary goal now. This leads to the conclusion that software security will even more important in the next years. As more clients get connected to the internet and especially more computers are waiting for incoming connections (like an \MTA\ in a home server), there are more possibilities to break into systems. Securing software systems will be done with increasing effort in future. + +``Plug-and-play''-able hardware with preconfigured software running can be expected to become popular. Like someone buys a set-top box to watch Pay-TV today, he might be buying a box acting as mail server in a few years. He plugs the power cable in, inserts his email address in a web interface and selects the clients (workstation computers or smart phones) to which mail should be send and from which mail is accepted to receive. That's all. It would just work then, like everyone expects it from a set-top box today. + +Containing secure and robust software is a pre-requisite for such boxes to make that vision possible. + +It seems as if all widely used \mta{}s provide good security nowadays. \name{qmail}'s architecture, also used in \name{postfix}, is generally seen to be conceptually more secure, however. + +In summary: easy configuration, aswell as the somehow opposed flexibility will be important for future \mta{}s. Also will it be security, but not performance. \MTA{}s might become more commodity software, like web servers already are today, with the purpose to include it in many systems and the need of minimal configuration. + + + +\section{Differences in \freesw} + diff -r 4fabc8ac5538 -r e050221efd38 thesis/tex/3-MasqmailProject.tex --- a/thesis/tex/3-MasqmailProject.tex Fri Nov 14 18:13:14 2008 +0100 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,218 +0,0 @@ -\chapter{The \masqmail\ project} - -%TODO: have text by oliver here? - -\section{Purpose of \masqmail} - -\subsection{Target field} -Its original author, Oliver Kurth, sees \masqmail\ so: -\begin{quote} -MasqMail is a mail server designed for hosts that do not have a permanent internet connection eg. a home network or a single host at home. It has special support for connections to different ISPs. It replaces sendmail or other MTAs such as qmail or exim. -\end{quote} - -\masqmail\ is inteded to cover a specific niche: non-permanent internet connection and different \NAME{ISP}s. - -Although it can basically replace other \MTA{}s, it is not generally aimed to do so. The package description of \debian\citeweb{packages.debian:masqmail} states this more clearly by changing the last sentence to: -\begin{quote} -In these cases, MasqMail is a slim replacement for full-blown MTAs such as sendmail, exim, qmail or postfix. -\end{quote} -\masqmail\ is a good replacement ``in these cases'', but not generally, since is lacks features essential for running on mail servers. It is primarily not secure enough for being accessable from untrusted locations. - -The program is best used in home networks, which are non-permanently connected to the internet. \masqmail\ sends mail to local destinations, like users on the same machine and on other machines in the local net, immediately. Email to recipients outside the local net are queued when offline and sent when a online connection gets established. - -Further more does \masqmail\ respect online connections through different \NAME{ISP}s; a common thing for dial-up connections. In particular can different sender addresses be set, dependent on the \NAME{ISP} that is used. This prevents mail to be likely classified as spam. - - - -\subsection{Typical usage} -This section describes situations that make senseful use of \masqmail. - -A home network consisting of some workstations without a server. The network is connected to the internet by dial-up or broadband. Going online is initiated by computers inside the local net. \NAME{IP} addresses change at least once every day. - -Every workstation would be equiped with \masqmail. Mail transfer within the same machine or within the local net works straight forward. Outgoing mail to the internet is sent, to the concerning \NAME{ISP} for relaying, whenever the router goes online. Receiving of mail from outside needs to be done by a mail fetch program, like the \masqmail\ internal \NAME{POP3} client or \name{fetchmail} for example. The configuration for \masqmail\ would be the same on every computer, except the hostname. - -For the same network but having a server, one could have \masqmail\ running on the server and using simple forwarders (see \ref{subsec:relay-only}) to the server on the workstations. This setup does only support mail transfer to the server, but not back to a workstation; also sending mail to another user on the same workstation is not possible. - -A better setup is to run \masqmail\ on every machine %FIXME - - - -\subsection{What makes it special} - -As main advantage, \masqmail\ makes it easy to set up an \MTA\ on workstations or notebooks without the need to do complex configuration or to be an mail server expert. - -Workstations use %FIXME - - -\subsection{Alternatives?} -% http://anfi.homeunix.org/sendmail/dialup10.html - -\section{History} -%TODO: let oliver prove read it! -%FIXME: add references -%FIXME: where does the name come from: masqdialer (guessed) - -The date of the first release (version 0.0.1) is unknown. -The only information available is, that it was packaged for \debian\ at 15\nth\ of September in 1999. -Further releases were made every few weeks or month during 2000, 2001 and 2002. -Development ended in mid-2003 in a hard stop. -The last ordinary release known to me is version 0.2.20, released on 4\nth\ of June in 2003. - -During the time of development, Oliver released 53 versions. -That means a new release in less than every 20 days in average! - -Mentionable are the four \emph{beta} releases of version 0.1.8 (named with the trailing letters `a' to `d') in winter 2000/2001 and the security-fix 0.1.15.1 in 2002. - -One extra release (version 0.2.21) was made by him in November 2005. -This one is only available from the \debian\ pool. -Comparing it to version 0.2.20 shows, that no source code was altered. -Only building documents (like Makefiles) and \debian\ packageing documents were changed. -That leeds to the assumption that this last release was specificly created for the needs of \debian---to fix some errors in the package. - -In May 2000 the minor version number increased to `1'. -Nothing special is mentioned in the documentation about that. -When it increased again to start the 0.2.x releases, Oliver titled them as the ``development branch'' of \masqmail. -At that second time, he started developing the 0.2.x ``development branch'', continuing to work on the 0.1.x series. -His parallel work on both branches lasted for four month, and one additional last release, numbered 0.1.17, one more year later. - - - -\section{Taking \masqmail} - - - - -\section{About \freesw\ projects} - -% http://www.faqs.org/docs/artu/ - -There are several differences between \freesw\ projects and projects about proprietary software. -To understand \freesw\ projects, one needs to understand \freesw\ itself first. - -\subsection{About \freesw} -The term ``Free Software'' was coined by the \name{Free Software Foundation} (short: \NAME{FSF}), founded by Richard~M.\ Stallman (known as ``RMS'') in 1985. -Although various licenses make software free, none of them represents the thinking of \freesw\ like the the \GNU\ \gpl\ (short: \GPL). Its first version was written by Stallman in 1989. -One could say, the \GPL\ catalized the \name{Free Software movement}. - -% http://www.fsf.org/about/what-is-free-software - -After all, the \GPL\ was not the first \freesw\ license used. -The \name{MIT License} (or \name{X Consortium License}) for example is older; published in 1988. -Licenses providing the same rights have been used since long time ago. -But none of them was so often (re)used by other projects---thus gattering less awareness. -Further more was the \GPL\ created to be a \emph{general} license for all kinds of programs, unlike most other licenses written for one particular program. - -\freesw\ gives freedoms to its users. -In contrast to proprietary software restricting the users freedom. -The freedoms (or rights) the user has are stated in the \name{Free Software Definition} of the \NAME{FSF}. Namely these are: -% http://www.gnu.org/philosophy/free-sw.html -% http://www.fsf.org/licensing/essays/free-sw.html -\begin{enumerate} - \item The freedom to run the program, for any purpose (freedom 0). - \item The freedom to study how the program works, and adapt it to your needs (freedom 1). Access to the source code is a precondition for this. - \item The freedom to redistribute copies so you can help your neighbor (freedom 2). - \item The freedom to improve the program, and release your improvements to the public, so that the whole community benefits (freedom 3). Access to the source code is a precondition for this. -\end{enumerate} - - -\subsection{The term ``Open Source''} -\name{Open Source Software} often stands for the same as \freesw. -But there is an essential difference: \name{Open Source} focuses on the availability of source code, while \freesw\ is about freedoms for people. - -\name{Open Source Software} is a subset of \freesw, meaning: All \freesw\ is \name{Open Source}, but there exists \name{Open Source Software} that is not free. - -% http://www.gnu.org/philosophy/open-source-misses-the-point.html -% http://catb.org/~esr/open-source.html - - -\subsection{Development of \freesw} -Having source code available and the right to modify it, encouridges programmers to actually do so. -Their modifications are manifoldly. -Some tailor the software to their needs. -Some add features. -Some do it just for fun. -There are no limitations---whoever wants to, may work on it. - -Since the boom of the internet, \freesw\ typically is developed by an open community of programmers interested in the software. -The process of development is watchable by everyone. - -The other, now less common, method is a more closed group, developing in a ``sealed'' room, but releasing finished versions to the public. - -Eric~S.\ Raymond discusses about these methods, which he named \name{the bazaar} and \name{the cathedral} \cite{catb}. - -The following text will focus on the ``bazaar'' model. - - -\subsection{The role of the community} -\freesw\ projects rise and fall with their community! - -Most \freesw\ programs are developed by a very small group of programmers, often only one person. -But they are used by many people. -In between the programmers and the users, are people located who are a bit of both. -These are the ones that write documentation, find bugs and probably even fix it. -They discuss on mailing lists, bulletin boards and \NAME{IRC} chats. -The program is often spread by their ``advertising''. - -The \emph{community} consists of the actual developers and all users that contribute to the program. -Contribution can be one of the described ways, or others like providing a server for the project website for example. - -\emph{Community} is everyone who is in contact through the project. -Be it on the mailing list, the discussion board, or by telling the developers about a new feature wanted. - -There will hardly be a community if no communication channels are available. -If the development team does not provide them, there is a chance that encouraged users set them up on their own. -But this is rare and the program needs to be very popular. %TODO: maybe include an example here (w3m?) - -Projects without a good community tend to die sooner or later. - - -\subsection{Evolution of a community} -Let us look at the process a community establishes: In most times it's only one who has an idea, in the beginning. -He starts developing. -When others get in contact with the project, there may be some who are so much interested that they start co-developing. -Others report bugs, and some only use the program. - -After some time, one will find a small group of core developers, a larger group of contributers (bugs, patches, documentation) and a very large group of users. -The size ratio of the groups vary by type of project. - -One should have that in mind, when starting a \freesw\ project. - - -\subsection{Creating a strong community} -Building up a good community needs some effort of the main developers. -%TODO: search for documents about this topic - -First communication channels need to be set up, to enable the growth of a community. - -Second, development should be visible by everyone who is interested in it. -Time between work done on the project and its visibility to the public should be kept short. -This makes it interesting for other developers to join. -Developers are the core of a community. - -Third, there is a rule of thumb that should be followed: ``Release early, release often!'' \cite{catb}. -Releases are (more) stable versions, primary for users. -They should be created, frequently. -People will more likely use programs of active projects. - -Fourth, the developers should try to get the users ``in the boat''. -Good communities have a large group of users that do not only receive, but also give something back to the project. -The project leaders should motivate users to contribute. -This unlocks a big work force and gets lot of unexiting work done. - -Fifth, documentation matters. -Good documentation makes it easy for users and developers to start. -And it helps to avoid a lot of unsatisfaction. -Documentation is something that shows quality and that people care about the project. - -And sixth, project leaders should be good souvereigns. -They should try to be fair, to motivate, be visionaires and try to put power and work on many shoulders. - -Not to forget: Every work that was done, every contribution that was made and every idea received needs to be honored in an appropriate way! -Volunteer work lives by acknowledgement of the effort spent. - - - - - -\section{Project infrastructure} - diff -r 4fabc8ac5538 -r e050221efd38 thesis/tex/4-CodeAnalysis.tex --- a/thesis/tex/4-CodeAnalysis.tex Fri Nov 14 18:13:14 2008 +0100 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,29 +0,0 @@ -\chapter{Code analysis} - - -\section{Architecture} -Like its anchestor \sendmail, \masqmail\ is a monolitic program. It consists of only one \emph{setuid root}\footnote{Runs as user root, no matter which user invoked it.}\index{setuid root} binary file, named \path{masqmail}. All functionality is included in it; of course some more comes from dynamic libraries linked. - - - -\subsection{Structure} -The \masqmail\ executable can be called under various names for \name{sendmail-compatibility} reasons. This is commonly organized by creating symbolic links with with different names to the \masqmail\ executable. These are \path{/usr/lib/sendmail} and \path{/usr/sbin/sendmail} because many programs expect a \mta\ to be located there. Further more \sendmail\ provides shortcuts by calling it with a different name instead of supplying command line arguments. The best known of it is \path{mailq}, which is equivilent to calling the \MTA\ with the argument \verb+-bq+. \masqmail\ reacts to the names \path{mailq}, \path{smtpd}, \path{mailrm}, \path{runq}, \path{rmail}, and \path{in.smtpd}. The last four are an addition to \sendmail. Not implemented is the name \path{newaliases} because it is not relevant to \masqmail. To provide the command nonetheless, one may write a shell script located at \path{/usr/bin/newaliases}, that simply invokes \verb+masqmail -bi+. - -%masqmail: mailq, mailrm, runq, rmail, smtpd/in.smtpd -%sendmail: hoststat, mailq, newaliases, purgestat, smtpd - -\masqmail\ is written in the \NAME{C} programming language. The program, as of version 0.2.21, consists of 34 source code and eight header files, containing about 9,000 lines of code\footnote{Measured with \name{sloccount} by David A.\ Wheeler.}. Additionally, it includes a \name{base64} implementation (about 300 lines) and \name{md5} code (about 150 lines). For systems that do not provide \name{libident}, this library is distributed as well (circa 600 lines); an available shared library however has higher precedence in linking. - -The only mandatory dependency is \name{glib}---a cross-platform software utility library, originated in the \NAME{GTK+} project. It provides safer replacements for many standard library functions. (The unsafe \verb+sprintf()+ is one example.) Also it offers handy data containers, easy-to-use implementations of data structures, and much more. - -With \masqmail\ comes the small tool \path{mservdetect}; it helps setting up a configuration that uses the \name{mserver} system to detect the online state. Two other binaries get compiled for testing purposes: \path{readtest} and \path{smtpsend}. All three programms use \masqmail\ source code; they only add a file with a \verb+main()+ function each. - -\masqmail\ does not provide an interface for modules with additional functionality. There exists no add-on or module system. But the code is separated by function to the various source files, and some functional parts can be included or excluded by defining symbols. This means adding some argument (like \verb+--enable-maildir+) to the \verb+configure+ call. Thus the concerning code gets not removed by the preprocessor. - - - - -\section{Code quality} - - -\section{Security} diff -r 4fabc8ac5538 -r e050221efd38 thesis/thesis.sty --- a/thesis/thesis.sty Fri Nov 14 18:13:14 2008 +0100 +++ b/thesis/thesis.sty Fri Nov 14 18:16:26 2008 +0100 @@ -12,7 +12,7 @@ \setlength{\parindent}{0em} \setlength{\parskip}{1.0ex plus 1.0ex minus 0.5ex} - \setcounter{tocdepth}{1} + \setcounter{tocdepth}{2} \pagestyle{headings} %\pagestyle{fancy} diff -r 4fabc8ac5538 -r e050221efd38 thesis/thesis.tex --- a/thesis/thesis.tex Fri Nov 14 18:13:14 2008 +0100 +++ b/thesis/thesis.tex Fri Nov 14 18:16:26 2008 +0100 @@ -29,8 +29,7 @@ \include{tex/1-Introduction} \include{tex/2-MailTransferAgents} -\include{tex/3-MasqmailProject} -\include{tex/4-CodeAnalysis} +\include{tex/3-MarketAnalysis} \include{tex/5-Improvements} \include{tex/6-Release} \include{tex/7-Summary}