<title>Updated design notes on fetchmail</title>
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out in this document. It is therefore a sort of a TODO document, until
the necessary code revisions have been made.</p>
+<h2>Security</h2>
+
+<p>Fetchmail was handed over in a pretty poor shape, security-wise. It will
+happily talk to the network with root privileges, use sscanf() to read
+remotely received data into fixed-length stack-based buffers without
+length limitation and so on. A full audit is required and security
+concepts will have to be applied. Random bits are:</p>
+
+<ul>
+ <li>code talking to the network does not require root privileges and
+ needs to run without root permissions</li>
+ <li>all input must be validated, all strings must be length checked,
+ all integers range checked</li>
+ <li>all types will need to be reviewed whether they are signed or
+ unsigned</li>
+</ul>
+
<h2>SMTP forwarding</h2>
-<p>Fetchmails multidrop and rewrite options will process addresses
+<p>Fetchmail's multidrop and rewrite options will process addresses
received from remote sites. Special care must be taken so these
features cannot be abused to relay mail to foreign sites.</p>
<h3>Why we need client-side tracking</h3>
<p>ESR asserted that server-side state were essential and those persons
-repsonsible for removing the LAST command from POP3 deserved to
+responsible for removing the LAST command from POP3 deserved to
suffer. ESR is right in stating that the POP3 UID tracks which messages
have been read <em>by this client</em> – and that is exactly what
we need to do.</p>
-<p>If fetchmail is supposed to retrieve all
-mail from a mailbox reliably, without being disturbed by someone
-occasionally using another client on another host, or a webmailer, or
-similar, then <em>client</em>-side tracking of the state is
-indispensable. This is also needed to match behavior to ETRN and ODMR.</p>
+<p>If fetchmail is supposed to retrieve all mail from a mailbox
+reliably, without being disturbed by someone occasionally using another
+client on another host, or a webmailer, or similar, then
+<em>client</em>-side tracking of the state is indispensable. This is
+also needed to match behavior to ETRN and ODMR or to support read-only
+mailboxes in --keep mode.</p>
<h3>Present and future</h3>
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