docs/diploma

annotate thesis/tex/4-MasqmailsFuture.tex @ 133:653ff21b89be

the last commit had a bad message better is: tagged person names new content for MTA comparison reworked some more content
author meillo@marmaro.de
date Wed, 10 Dec 2008 16:56:37 +0100
parents a83a29e10b10
children c60b164bfd3c
rev   line source
meillo@109 1 \chapter{\masqmail's present and future}
meillo@93 2
meillo@93 3 \section{Existing features}
meillo@117 4 This overview regards \masqmail\ version 0.2.21, the state this document starts off.
meillo@93 5
meillo@132 6 \masqmail\ is an \MTA, therefor it accepts mail on the command line and via \SMTP. Mail queueing and alias expansion is supported. \masqmail\ is able to deliver mail to local mailboxes (in \name{mbox} or \name{maildir} format) or pass it to a \name{mail delivery agent} (like \name{procmail}). Mail destinated to remote locations is sent via \SMTP. Outgoing \SMTP\ connections feature \name{SMTP-Auth} and \name{SMTP-after-POP} authentication, but incoming \SMTP\ does not.
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meillo@93 8 As \masqmail\ is focused on non-permanent Internet connections, online state can be queried by three methods: reading from a file, reading the output of a command, or by asking an \name{mserver}. Each method may return a string indicating one of the available routes being online, or returning nothing to indicate offline state.
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meillo@93 10 Delivery to recipients on the local host or in local nets is done at once; delivery to recipients on the Internet is only done when being online, and queued otherwise. Each online route may have a different mail server to which mail is relayed. Return address headers are modified appropriate if wished.
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meillo@93 12 Additional to the \mta\ job, \masqmail\ also offers mail retrieval services with being a \NAME{POP3} client. Thus it can fetch mail from remote locations, dependent on the active online route.
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meillo@109 16 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+.
meillo@109 17
meillo@109 18 %masqmail: mailq, mailrm, runq, rmail, smtpd/in.smtpd
meillo@109 19 %sendmail: hoststat, mailq, newaliases, purgestat, smtpd
meillo@109 20
meillo@109 21 \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.
meillo@109 22
meillo@109 23 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.
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meillo@109 25 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.
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meillo@109 27 \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.
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meillo@132 33 \section{Discussion/Ideas}
meillo@132 34
meillo@132 35
meillo@132 36 << plans to get masqmail more popular again (if that is the goal) >> %FIXME
meillo@132 37
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meillo@132 39 \subsection{Architecture}
meillo@132 40
meillo@132 41 << architecture diagram >>
meillo@132 42
meillo@132 43 (ssl) -> msg-in (local or remote protocol handlers) -> spam-filter (and more) -> queue -> msg-out (local-delivery by MDA, or remote-protocol-handlers) -> (ssl)
meillo@132 44
meillo@132 45 A design from scratch?
meillo@132 46
meillo@132 47 << what would be needed (effort) >> %FIXME
meillo@132 48
meillo@132 49 << would one create it at all? >> %FIXME
meillo@132 50
meillo@132 51 << should it be done? >> %FIXME
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meillo@132 55 \subsection{local mail delivery}
meillo@132 56 But for example delivery of mail to local users is \emph{not} what \mta{}s should care about, although most \MTA\ are able to deliver mail, and many do. (\name{mail delivery agents}, like \name{procmail} and \name{maildrop}, are the right programs for this job.)
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meillo@132 60 \subsection{various protocols}
meillo@132 61 protocols like \NAME{SMTP} and \NAME{UUCP}, between which mail is transferred.\footnote{\sendmail{}'s initial purpose was moving mail between \NAME{UUCP}, \NAME{SMTP}, and \name{Berknet}.}
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meillo@132 68 http://fanf.livejournal.com/50917.html %how not to design an mta - the sendmail command
meillo@132 69 http://fanf.livejournal.com/51349.html %how not to design an mta - partitioning for security
meillo@132 70 http://fanf.livejournal.com/61132.html %how not to design an mta - local delivery
meillo@132 71 http://fanf.livejournal.com/64941.html %how not to design an mta - spool file format
meillo@132 72 http://fanf.livejournal.com/65203.html %how not to design an mta - spool file logistics
meillo@132 73 http://fanf.livejournal.com/65911.html %how not to design an mta - more about log-structured MTA queues
meillo@132 74 http://fanf.livejournal.com/67297.html %how not to design an mta - more log-structured MTA queues
meillo@132 75 http://fanf.livejournal.com/70432.html %how not to design an mta - address verification
meillo@132 76 http://fanf.livejournal.com/72258.html %how not to design an mta - content scanning
meillo@132 77
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meillo@132 79
meillo@132 80 << concrete decisions based on results of the last 2 chapters >> %FIXME
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meillo@93 87 \section{Directions to go}
meillo@93 88
meillo@93 89 \subsection{\masqmail\ in five years}
meillo@93 90 \label{sec:masqmail-in-5-years}
meillo@93 91 Now how could \masqmail\ be like in, say, five years?
meillo@93 92
meillo@99 93 << requirements >> %FIXME
meillo@99 94
meillo@99 95 << which parts to do >> %FIXME
meillo@99 96
meillo@99 97 << how to make masqmail future-safe >> %FIXME
meillo@99 98
meillo@99 99 << how to advertise masqmail >> %FIXME
meillo@99 100
meillo@99 101 << difference for free software >> %FIXME
meillo@99 102
meillo@99 103 << why is it worth to revive masqmail? >> %FIXME
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meillo@93 110 \section{Work to do}
meillo@93 111
meillo@99 112 << which parts to take out and do within the thesis >> %FIXME
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meillo@133 114