Mercurial > docs > diploma
comparison thesis/tex/3-MailTransferAgents.tex @ 155:0b17f6e5edae
new books; websites to books
| author | meillo@marmaro.de |
|---|---|
| date | Tue, 16 Dec 2008 15:58:00 +0100 |
| parents | 5f7beb2142d6 |
| children | ee687abf386c |
comparison
equal
deleted
inserted
replaced
| 154:cc66f7f08e21 | 155:0b17f6e5edae |
|---|---|
| 72 The programs chosen are: \sendmail, \exim, \qmail, and \postfix. They are the most important representatives of the regarded group. Although \MTA\ statistics are rare, differ, and good data is hard to collect, these programs tend to stay near the top. | 72 The programs chosen are: \sendmail, \exim, \qmail, and \postfix. They are the most important representatives of the regarded group. Although \MTA\ statistics are rare, differ, and good data is hard to collect, these programs tend to stay near the top. |
| 73 | 73 |
| 74 | 74 |
| 75 \subsection{Market share analysis} | 75 \subsection{Market share analysis} |
| 76 | 76 |
| 77 Table \ref{tab:mta-market-share} shows the most used \MTA{}s determined by three different statistics. The first was done by Daniel~J.\ \person{Bernstein} (the author of \qmail) in 2001 \citeweb{djb:mta-stats}. The second is by \person{Simpson} and \person{Bekman} in 2007 and was published by \name{O'ReillyNet} \citeweb{oreillynet:mta-stats}. And the third is from \name{MailRadar.com} with unknown date\footnote{The footer of the website shows ``Copyright 2007'' but more likely does this refer to the whole website.} \citeweb{mailradar:mta-stats}. | 77 Table \ref{tab:mta-market-share} shows the most used \MTA{}s determined by three different statistics. The first was done by Daniel~J.\ \person{Bernstein} (the author of \qmail) in 2001 \cite{bernstein01}. The second is by \person{Simpson} and \person{Bekman} in 2007 and was published by \name{O'ReillyNet} \cite{simpson07}. And the third is from \name{MailRadar.com} with unknown date\footnote{The footer of the website shows ``Copyright 2007'' but more likely does this refer to the whole website.} \citeweb{mailradar:mta-stats}. |
| 78 | 78 |
| 79 \begin{table} | 79 \begin{table} |
| 80 \begin{center} | 80 \begin{center} |
| 81 \input{input/mta-market-share.tex} | 81 \input{input/mta-market-share.tex} |
| 82 \end{center} | 82 \end{center} |
| 95 It seems quite sure that the \name{MailRadar} statistics were published after 2001, caused by the \sendmail\ and \postfix\ shares. But to decide whether before or after the one from \name{O'Reilly} would be just a guess. | 95 It seems quite sure that the \name{MailRadar} statistics were published after 2001, caused by the \sendmail\ and \postfix\ shares. But to decide whether before or after the one from \name{O'Reilly} would be just a guess. |
| 96 | 96 |
| 97 | 97 |
| 98 \subsection{The four major Free Software MTAs} | 98 \subsection{The four major Free Software MTAs} |
| 99 | 99 |
| 100 Now follows a small introduction to the five programs chosen for comparison, except \masqmail\ which already was introduced in chapter \ref{chap:introduction}. Longer introductions, including analysis and comparison, were written by Jonathan de \person{Boyne Pollard} \citeweb{jdebp}. | 100 Now follows a small introduction to the five programs chosen for comparison, except \masqmail\ which already was introduced in chapter \ref{chap:introduction}. Longer introductions, including analysis and comparison, were written by Jonathan de \person{Boyne Pollard} \cite{jdebp}. |
| 101 | 101 |
| 102 | 102 |
| 103 | 103 |
| 104 \subsubsection*{sendmail} | 104 \subsubsection*{sendmail} |
| 105 \label{sec:sendmail} | 105 \label{sec:sendmail} |
| 137 \qmail\ first introduced many innovative concepts in \mta\ design and is generally seen as the first security-aware \MTA\ developed. %fixme:ref | 137 \qmail\ first introduced many innovative concepts in \mta\ design and is generally seen as the first security-aware \MTA\ developed. %fixme:ref |
| 138 %fixme: what about mmdf? | 138 %fixme: what about mmdf? |
| 139 | 139 |
| 140 Since November 2007, \qmail\ is released in the \name{public domain} which makes it \freesw. The latest release is 1.03 from July 1998. | 140 Since November 2007, \qmail\ is released in the \name{public domain} which makes it \freesw. The latest release is 1.03 from July 1998. |
| 141 | 141 |
| 142 The programs homepages are \citeweb{qmail:homepage1} and \citeweb{qmail:homepage2}. Further information about \qmail\ is available with Dave \person{Sill}'s ``Life with qmail'' \citeweb{lifewithqmail}. | 142 The programs homepages are \citeweb{qmail:homepage1} and \citeweb{qmail:homepage2}. Further information about \qmail\ is available with Dave \person{Sill}'s ``Life with qmail'' \cite{lifewithqmail}. |
| 143 | 143 |
| 144 | 144 |
| 145 | 145 |
| 146 \subsubsection*{postfix} | 146 \subsubsection*{postfix} |
| 147 \label{sec:postfix} | 147 \label{sec:postfix} |
| 158 | 158 |
| 159 | 159 |
| 160 | 160 |
| 161 \section{Comparison of MTAs} | 161 \section{Comparison of MTAs} |
| 162 | 162 |
| 163 This section does not try to provide an overall \MTA\ comparison, because this is already done by others. Remarkable comparisons are the one by Dan \person{Shearer} \cite{shearer06} and a discussion on the mailing list \name{plug@lists.q-linux.com} \citeweb{plug:mtas}. Tabulary overviews may be found at \citeweb{mailsoftware42}, \citeweb{wikipedia:comparison-of-mail-servers}, and \citeweb[section 1.9]{lifewithqmail}. | 163 This section does not try to provide an overall \MTA\ comparison, because this is already done by others. Remarkable comparisons are the one by Dan \person{Shearer} \cite{shearer06} and a discussion on the mailing list \name{plug@lists.q-linux.com} \cite{plug:mtas}. Tabulary overviews may be found at \citeweb{mailsoftware42}, \citeweb{wikipedia:comparison-of-mail-servers}, and \cite[section 1.9]{lifewithqmail}. |
| 164 | 164 |
| 165 Here provided is an overview on a selection of important properties, covering the four previously introduced programs. The data comes from the above stated sources and is collected in table \ref{tab:mta-comparison}. | 165 Here provided is an overview on a selection of important properties, covering the four previously introduced programs. The data comes from the above stated sources and is collected in table \ref{tab:mta-comparison}. |
| 166 | 166 |
| 167 \begin{table} | 167 \begin{table} |
| 168 \begin{center} | 168 \begin{center} |
| 174 | 174 |
| 175 | 175 |
| 176 \subsection{Architecture} | 176 \subsection{Architecture} |
| 177 | 177 |
| 178 Architecture is most important when comparing \MTA{}s. Many other properties of a program depend on its architecture. %fixme: add ref? | 178 Architecture is most important when comparing \MTA{}s. Many other properties of a program depend on its architecture. %fixme: add ref? |
| 179 Munawar \person{Hafiz} \cite{hafiz05} discusses in detail on \mta\ architecture, comparing \sendmail, \qmail, \postfix, and \name{sendmail X}. Jonathan de \person{Boyne Pollard}'s \MTA\ review \citeweb{jdebp} is a source too. | 179 Munawar \person{Hafiz} \cite{hafiz05} discusses in detail on \mta\ architecture, comparing \sendmail, \qmail, \postfix, and \name{sendmail X}. Jonathan de \person{Boyne Pollard}'s \MTA\ review \cite{jdebp} is a source too. |
| 180 | 180 |
| 181 Two different architecture types show off: monolithic and modular \mta{}s. | 181 Two different architecture types show off: monolithic and modular \mta{}s. |
| 182 | 182 |
| 183 Monolithic \MTA{}s are \sendmail, \name{smail}, \exim, and \masqmail. They all consist of one single \emph{setuid root}\footnote{\emph{setuid root} lets a program run with the rights of its owner, here root. This is considered a security risk.} binary which does all the work. | 183 Monolithic \MTA{}s are \sendmail, \name{smail}, \exim, and \masqmail. They all consist of one single \emph{setuid root}\footnote{\emph{setuid root} lets a program run with the rights of its owner, here root. This is considered a security risk.} binary which does all the work. |
| 184 | 184 |
| 185 Modular \MTA{}s are \NAME{MMDF}, \qmail, \postfix, and \name{MeTA1}. They consist of several programs, each doing a part of the overall job. The different programs run with the least permissions the need, and \emph{setuid root} needs not to be used. | 185 Modular \MTA{}s are \NAME{MMDF}, \qmail, \postfix, and \name{MeTA1}. They consist of several programs, each doing a part of the overall job. The different programs run with the least permissions the need, and \emph{setuid root} needs not to be used. |
| 186 | 186 |
| 187 The architecture does not directly define the program's security, but ``[t]he goal of making a software secure can be better achieved by making the design simple and easier to understand and verify''\cite[chapter 6]{hafiz05}. \exim, though being monolithic, has a fairly clean security record. But it is very hard to keep the security up, as the program growth. Wietse \person{Venema} (the author of \postfix) says, the architecture enabled \postfix\ to grow without running into security problems. \citeweb[page 13]{venema:postfix-growth} | 187 The architecture does not directly define the program's security, but ``[t]he goal of making a software secure can be better achieved by making the design simple and easier to understand and verify''\cite[chapter 6]{hafiz05}. \exim, though being monolithic, has a fairly clean security record. But it is very hard to keep the security up, as the program growth. Wietse \person{Venema} (the author of \postfix) says, the architecture enabled \postfix\ to grow without running into security problems. \cite[page 13]{venema:postfix-growth} |
| 188 | 188 |
| 189 The modular design, with each sub-program doing one part of the overall job, is applied \name{Unix Philosophy}. The Unix Philosophy \cite{gancarz95} demands ``small is beautiful'' and ``make each program do one thing well''. Monolithic \MTA{}s fail here. | 189 The modular design, with each sub-program doing one part of the overall job, is applied \name{Unix Philosophy}. The Unix Philosophy \cite{gancarz95} demands ``small is beautiful'' and ``make each program do one thing well''. Monolithic \MTA{}s fail here. |
| 190 | 190 |
| 191 Today modular \mta\ architectures are the state-of-the-art. | 191 Today modular \mta\ architectures are the state-of-the-art. |
| 192 | 192 |