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3<title>Frequently Asked Questions for Samhain</title>
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120<body>
121<div class="body">
122<p style="text-align: center; background: #ccc; border: 1px solid #2d5588;"><a
123 style="text-decoration: none;"
124 href="http://www.la-samhna.de/samhain/">samhain file integrity
125 scanner</a>&nbsp;|&nbsp;<a style="text-decoration: none;"
126 href="http://www.la-samhna.de/samhain/s_documentation.html">online
127 documentation</a></p>
128<br><center><h1><a name="FAQ-top">Frequently Asked Questions for Samhain</a></h1></center>
129<br><center><h2>Rainer Wichmann</h2></center>
130<hr>
[19]131<p><i>FAQ Revised: Tuesday 31 January 2006 21:28:35</i></p>
[1]132<hr><h2>Table of Contents</h2>
133<dl>
134<dt><b>1. Most frequently</b></dt>
135<dd><ul>
136<li><a href="#Most frequently0">1.1. Owner not trustworthy / Group writeable and member not trustworthy</a></li>
137<li><a href="#Most frequently1">1.2. samhain exits with the message &quot;Untrusted path&quot; for config/log/pid/database files</a></li>
138<li><a href="#Most frequently2">1.3. It does not log anything / Can't stop logging to console</a></li>
139<li><a href="#Most frequently3">1.4. Client cannot self-resolve, but nslookup works fine</a></li>
140</ul></dd>
141<dt><b>2. Build and install</b></dt>
142<dd><ul>
143<li><a href="#Build and install0">2.1. [Fedora Core] Cannot compile with --enable-khide</a></li>
144<li><a href="#Build and install1">2.2. [Fedora Core] Cannot compile with --with-kcheck</a></li>
145<li><a href="#Build and install2">2.3. &quot;make&quot; loops infinitely !</a></li>
146<li><a href="#Build and install3">2.4. Why does static compiling (<code>--enable-static</code>) on Solaris fail ?</a></li>
147<li><a href="#Build and install4">2.5. Compilation fails with '/usr/bin/ld: cannot find -lnss_files'</a></li>
148<li><a href="#Build and install5">2.6. The executable is corrupted after installation</a></li>
149<li><a href="#Build and install6">2.7. --enable-xml-log has no effect</a></li>
150<li><a href="#Build and install7">2.8. ./install-sh: strip: not found (Solaris)</a></li>
[19]151<li><a href="#Build and install8">2.9. What is sh_tiger1.s?</a></li>
[1]152</ul></dd>
153<dt><b>3. File checking</b></dt>
154<dd><ul>
155<li><a href="#File checking0">3.1. How can I exclude a (sub-)directory ?</a></li>
156<li><a href="#File checking1">3.2. In messages about policy violations, what does the code after POLICY [XYZ]
157mean ?</a></li>
158<li><a href="#File checking2">3.3. Does samhain support prelink ?</a></li>
159<li><a href="#File checking3">3.4. I get error messages about 'subdirectory count != hardlinks'</a></li>
160</ul></dd>
161<dt><b>4. Client/Server</b></dt>
162<dd><ul>
163<li><a href="#Client/Server0">4.1. I don't want to poke a hole into my firewall to let the client connect to the server !</a></li>
164<li><a href="#Client/Server1">4.2. The client sends 127.0.0.1 (or some other numerical address) as its name to the log server</a></li>
165<li><a href="#Client/Server2">4.3. The server wants to send rc.ip-adress rather than rc.fqdn to the client</a></li>
166<li><a href="#Client/Server3">4.4. Cannot resolve client name host=XXX</a></li>
167<li><a href="#Client/Server4">4.5. Cannot resolve socket peer IP for client host=XXX peer=YYY</a></li>
168<li><a href="#Client/Server5">4.6. Reverse lookup of socket peer failed host=XXX peer=YYY obj=ZZZ</a></li>
169<li><a href="#Client/Server6">4.7. No socket peer alias matches client name host=XXX peer=YYY</a></li>
170<li><a href="#Client/Server7">4.8. Session key negotiation failed</a></li>
171<li><a href="#Client/Server8">4.9. Invalid connection attempt: Not in client list</a></li>
172<li><a href="#Client/Server9">4.10. Invalid connection attempt: Session key mismatch</a></li>
173<li><a href="#Client/Server10">4.11. How do I update the file signature database ?</a></li>
174<li><a href="#Client/Server11">4.12. Time limit exceeded</a></li>
175<li><a href="#Client/Server12">4.13. Invalid connection attempt: Signature mismatch</a></li>
176<li><a href="#Client/Server13">4.14. [Server] PANIC .. Address already in use&nbsp; &nbsp;subroutine=bind</a></li>
177</ul></dd>
178<dt><b>5. Email</b></dt>
179<dd><ul>
180<li><a href="#Email0">5.1. Reverse lookup failed</a></li>
181<li><a href="#Email1">5.2. From daemon@example.com</a></li>
182<li><a href="#Email2">5.3. How do I define more than one email addresses ?</a></li>
183</ul></dd>
184<dt><b>6. Misc</b></dt>
185<dd><ul>
186<li><a href="#Misc0">6.1. Error message: &quot;Invalid line XYZ in configuration file&quot;</a></li>
187<li><a href="#Misc1">6.2. Why do I get a local logfile if I log to the server ?</a></li>
188<li><a href="#Misc2">6.3. Why is there no NIS support with a static samhain executable on Linux ?</a></li>
189<li><a href="#Misc3">6.4. Why do I get hundreds of messages about modified CTIME ?</a></li>
190<li><a href="#Misc4">6.5. PANIC &mdash; File not accessible</a></li>
191<li><a href="#Misc5">6.6. How can I avoid error messages for invalid UIDs (no such user) ?</a></li>
192<li><a href="#Misc6">6.7. [Redhat] The /etc/init.d/(samhain|yule) init script hangs</a></li>
193<li><a href="#Misc7">6.8. The /etc/init.d/(samhain|yule) init script exits with: execvp: No such file or directory</a></li>
194<li><a href="#Misc8">6.9. Why am I not receiving the &quot;BEGIN LOGKEY&quot; message by email ?</a></li>
195<li><a href="#Misc9">6.10. Why does console logging fail if I compile with
196 <code>--enable-(micro-)stealth</code> ?</a></li>
197<li><a href="#Misc10">6.11. I need a list for my schedule !</a></li>
198<li><a href="#Misc11">6.12. The hiding kernel module has no effect !</a></li>
199<li><a href="#Misc12">6.13. What does the message &quot;Large lstat/open overhead&quot; mean ?</a></li>
200<li><a href="#Misc13">6.14. What does the message &quot;Device not available path=/dev/random&quot; mean ? I have /dev/random !</a></li>
201<li><a href="#Misc14">6.15. Logging to an external program fails; the program receives no data
202 on stdin !</a></li>
203<li><a href="#Misc15">6.16. SIGILL on AIX</a></li>
204</ul></dd>
205<dt><b>7. Database</b></dt>
206<dd><ul>
207<li><a href="#Database0">7.1. Why are client messages corrupted / incompletely stored in the DB ?</a></li>
208<li><a href="#Database1">7.2. I want / don't want the server timestamps (for client messages) in the SQL database</a></li>
209<li><a href="#Database2">7.3. I don't want the client TIMESTAMP messages in the SQL database</a></li>
210<li><a href="#Database3">7.4. What does the log_ref field mean ?</a></li>
[19]211<li><a href="#Database4">7.5. How can I check what is in the database ?</a></li>
[1]212</ul></dd>
213</dl>
214<hr><h2>1. Most frequently</h2>
215<dl>
216<dt><b><a name="Most frequently0">1.1. Owner not trustworthy / Group writeable and member not trustworthy</a></b></dt>
217<dd>An untrusted user (might be an untrusted group member
218 for group writeable files/directories) owns or can write to an
219 element in the path listed in the error message. This concerns
220 the configuration file, the log file, and the database file.
221 The offending element in the path is identified as obj=/xxx in the
222 error message.
223 To fix the problem, see next entry.<br><br></dd>
224<dt><b><a name="Most frequently1">1.2. samhain exits with the message &quot;Untrusted path&quot; for config/log/pid/database files</a></b></dt>
225<dd>Paths to critical
226 files (e.g. the configuration file) must be writeable by trusted users
227 only.
228 If a path element is group writeable, all group members must be trusted.
229 By default, only <i>root</i> and the (effective) <i>user</i> of
230 the program are trusted. To add trusted users, use the compile time
231 option
232<div class="block"><pre>
233$ ./configure --with-trusted=0,...
234</pre></div>
235 or the configure file option:
236<div class="block"><pre>
237[Misc]
238TrustedUser=username
239</pre></div>
240If the path to the configuration file itself is writeable
241 by other users than <i>root</i> and the
242 <i>effective user</i>
243 these must be defined as trusted already
244 at compile time.<br><br></dd>
245<dt><b><a name="Most frequently2">1.3. It does not log anything / Can't stop logging to console</a></b></dt>
246<dd>(1) There is a section in the manual dealing with
247logging and filtering.<br />
248
249(2) To log to the console:
250<div class="block"><pre>
251$ samhain -p info ...
252</pre></div>
253or in the configuration file:
254<div class="block"><pre>
255[Log]
256PrintSeverity=info
257</pre></div>
258
259To <i>stop</i> logging to the console:
260<div class="block"><pre>
261$ samhain -p none ...
262</pre></div>
263or in the configuration file:
264<div class="block"><pre>
265[Log]
266PrintSeverity=none
267</pre></div>
268Defining <tt>/dev/null</tt> as console device works as well, but
269is a bad idea, because samhain will open the device and write (i.e. it is
270a very inefficient method).<br><br></dd>
271<dt><b><a name="Most frequently3">1.4. Client cannot self-resolve, but nslookup works fine</a></b></dt>
272<dd><ul>
273<li>Nslookup is a program to query Internet domain name servers.
274</li>
275<li>Applications (like samhain) are not supposed to query DNS servers
276 directly. Rather, they are supposed to query the resolver library that:
277 <ul>
278 <li>is provided by the operating system,</li>
279 <li>configured by the system administrator,</li>
280 <li>may use several different method to determine host names, as
281 configured in <tt>/etc/nsswitch.conf</tt>, and</li>
282 <li>usually is configured to give precedence to
283 the <tt>/etc/hosts</tt> file.</li>
284 </ul>
285</li>
286<li>Therefore, whether nslookup gives correct answers may be completely
287 irrelevant. For self-resolving the own hostname, the resolver
288 library probably will use <tt>/etc/hosts</tt>, rather than
289 querying a DNS server.
290</li>
291</ul>
292<p>
293Below you can find some examples of good and bad <tt>/etc/hosts</tt> files:
294</p>
295<div class="block"><pre>
296 # CORRECT
297 #
298 127.0.0.1 localhost
299 xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
300</pre></div>
301
302<div class="block"><pre>
303 # CORRECT
304 #
305 127.0.0.1 localhost.localdomain localhost
306 xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
307</pre></div>
308
309<div class="block"><pre>
310 # BAD
311 #
312 127.0.0.1 myhost.mydomain.tld localhost
313 xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
314</pre></div>
315
316<div class="block"><pre>
317 # BAD
318 #
319 127.0.0.1 localhost myhost
320 xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
321</pre></div><br><br></dd>
322</dl>
323<hr><h2>2. Build and install</h2>
324<dl>
325<dt><b><a name="Build and install0">2.1. [Fedora Core] Cannot compile with --enable-khide</a></b></dt>
326<dd>The Fedora Core kernel is patched to unconditionally deny reading
327from /dev/kmem. Compiling the stealth kernel modules is not possible
328under these circumstances.<br><br></dd>
329<dt><b><a name="Build and install1">2.2. [Fedora Core] Cannot compile with --with-kcheck</a></b></dt>
330<dd>The Fedora Core kernel is patched to unconditionally deny reading
331from /dev/kmem. Checking the kernel for the presence of rootkits is
332not possible under these circumstances.<br><br></dd>
333<dt><b><a name="Build and install2">2.3. &quot;make&quot; loops infinitely !</a></b></dt>
334<dd>This may happen (e.g. when building via NFS for multiple architectures)
335 if the relative timestamps in the source directory are
336 wrong (time not in sync on different machines) or some intermediate
337 target is unusable (up-to-date, but built for a different OS). Use
338 &quot;touch * &amp;&amp; make distclean&quot; in the source directory
339 to recover.<br><br></dd>
340<dt><b><a name="Build and install3">2.4. Why does static compiling (<code>--enable-static</code>) on Solaris fail ?</a></b></dt>
341<dd>Ingo Rogalsky has provided the following information: It isn't possible
342 to link Samhain statically with Solaris. This
343 is a Solaris issue (see Sun Infodoc ID12624) and not a samhain problem.<br><br></dd>
344<dt><b><a name="Build and install4">2.5. Compilation fails with '/usr/bin/ld: cannot find -lnss_files'</a></b></dt>
345<dd>For Linux, this is a known problem with --enable-static if you compile
346 in MySQL support. The problem is that the
347 <tt>mysql_config</tt> that comes as part of the MySQL
348 distribution script incorrectly lists dependencies on
349 the libnss_files and libnss_dns libraries which are only available as
350 shared libraries, so the linker cannot find the static libraries.
351
352 You can check this by inspecting the output of
353 <code>mysql_config --libs</code>. The version of
354 <tt>mysql_config</tt> that comes with the RedHat mysql
355 RPM (RedHat 9) does not have this bug; the one distributed by the MySQL
356 people has. You can fix the problem by editing
357 <tt>mysql_config</tt>: search for the
358 <i>client_libs</i> variable, and remove all instances
359 of <i>-lnss_files</i> and <i>-lnss_dns</i>.<br><br></dd>
360<dt><b><a name="Build and install5">2.6. The executable is corrupted after installation</a></b></dt>
361<dd>The executable will get stripped during the installation. On
362 suitable systems (i386 Linux/FreeBSD currently), additionally
363 the &quot;sstrip&quot;
364 utility (copyright 1999 by Brian Raiter, under the GNU GPL)
365 will be used to strip the executable even more, to prevent
366 debugging with the GNU &quot;gdb&quot; debugger.
367 The &quot;strip&quot; utility cannot handle the resulting
368 executable, therefore trying to strip manually after installation
369 will corrupt the executable.<br><br></dd>
370<dt><b><a name="Build and install6">2.7. --enable-xml-log has no effect</a></b></dt>
371<dd>If you have compiled for stealth, you won't see much, because if
372 obfuscated, then both a 'normal' and an XML logfile look,
373 well ... obfuscated. Use <code>samhain -jL /path/to/logfile</code>
374 to view the logfile.<br><br></dd>
375<dt><b><a name="Build and install7">2.8. ./install-sh: strip: not found (Solaris)</a></b></dt>
376<dd>Install the SUNWbtool package.<br><br></dd>
[19]377<dt><b><a name="Build and install8">2.9. What is sh_tiger1.s?</a></b></dt>
378<dd>This is a precompiled assembly file for the i386 architecture
379generated from sh_tiger1.c using gcc 3.4.0 with the following options,
380that were found to generate the fastest code:
381<pre>
382 -O1 -fno-delayed-branch -fexpensive-optimizations -fstrength-reduce
383 -fpeephole2 -fschedule-insns2 -fregmove -frename-registers -fweb
384 -momit-leaf-frame-pointer -funroll-loops
385</pre>
386These options were determined using
387<a href="http://www.coyotegulch.com/products/acovea/">acovea</a> 5.1.1
388by Scott Robert Ladd. The file is provided as precompiled assembly
389because different versions of gcc can have very different performance,
390require different options to compile optimal code, and
391it would be impossible to maintain a library of optimal compile options
392for every version of gcc.<br><br></dd>
[1]393</dl>
394<hr><h2>3. File checking</h2>
395<dl>
396<dt><b><a name="File checking0">3.1. How can I exclude a (sub-)directory ?</a></b></dt>
397<dd><div class="block"><pre>
398[IgnoreAll]
399dir=-1/ignore/this/subdirectory
400</pre></div><br><br></dd>
401<dt><b><a name="File checking1">3.2. In messages about policy violations, what does the code after POLICY [XYZ]
402mean ?</a></b></dt>
403<dd>This code indicates which items are modified (e.g. C = checksum). You can
404find a description in section 5.4.9 in the user manual. It is there because
405then you can see in the message list of the Beltane web console what has been
406modified, without the need to look at the message in detail.<br><br></dd>
407<dt><b><a name="File checking2">3.3. Does samhain support prelink ?</a></b></dt>
408<dd>Yes. There is a special checking policy [Prelink]. Directories with
409prelinked executables / shared libraries (see /etc/prelink.conf) should be
410placed under this policy, rather than under the [ReadOnly] policy.<br><br></dd>
411<dt><b><a name="File checking3">3.4. I get error messages about 'subdirectory count != hardlinks'</a></b></dt>
412<dd>Some filesystems do not always follow the rule that the number
413of directory
414hardlinks equals the number of subdirectories. E.g. the root directory of
415reiserfs partitions generally seems to have two additional hardlinks.
416To account for such exceptions, you can either switch off the
417hardlink check globally, or specify exceptions:
418<div class="block"><pre>
419[Misc]
420# Switch off hardlink check
421#
422UseHardlinkCheck=no
423</pre></div>
424<div class="block"><pre>
425[Misc]
426# Specify exceptions for the hardlink check
427#
428HardlinkOffset=N:/path
429</pre></div>
430Here, N is the numerical offset (actual - expected hardlinks) for
431'/path'. For multiple exceptions, use
432this options multiple times (note that '/path N:/path2' would itself be a valid
433path, so using the option only once with multiple exceptions on the same line
434would be ambiguous).<br><br></dd>
435</dl>
436<hr><h2>4. Client/Server</h2>
437<dl>
438<dt><b><a name="Client/Server0">4.1. I don't want to poke a hole into my firewall to let the client connect to the server !</a></b></dt>
439<dd>Pat Smith has posted the following solution. On the client, create
440an iptable rule as follows (<i>note: you probably don't need this if you
441configure / compile in 127.0.0.1 as the server address</i>):
442<div class="block"><pre>
443iptables -t nat -A OUTPUT -p tcp -m tcp --dport 49777 -d <i>server-ip</i> -j REDIRECT
444</pre></div>
445
446On the server, create an ssh tunnel for each client outside the firewall:
447
448<div class="block"><pre>
449ssh -f -C -R 49777:localhost:49777 -N <i>client-ip</i>
450</pre></div>
451
452It is necessary that each client has a distinct name, and that the server
453knows the name of the client. With the setup above, each client will appear
454as &quot;localhost&quot; to the server, thus the server
455needs to trust the client name
456as reported by the client itself, and suppress all eroors on resolving
457this name to the apparent address. In the server configuration:
458
459<div class="block"><pre>
460[Misc]
461SetClientFromAccept = false
462SeverityLookup = debug
463</pre></div>
464
465Obviously, self-resolving must work on the client machine, otherwise
466you are in trouble (see next issue).<br><br></dd>
467<dt><b><a name="Client/Server1">4.2. The client sends 127.0.0.1 (or some other numerical address) as its name to the log server</a></b></dt>
468<dd>See 'Client cannot self-resolve' in the 'Most frequently' section<br><br></dd>
469<dt><b><a name="Client/Server2">4.3. The server wants to send rc.ip-adress rather than rc.fqdn to the client</a></b></dt>
470<dd>The client self-resolves to its ip address.
471See 'Client cannot self-resolve' in the 'Most frequently' section<br><br></dd>
472<dt><b><a name="Client/Server3">4.4. Cannot resolve client name host=XXX</a></b></dt>
473<dd><div class="block"><pre>
474The server must be able to determine the client name.
475This is because only authenticated connections from registered
476clients are allowed, and
477the server must be able to check the client hostname against the list of
478allowed hosts, and look up the password verifier for that
479host.
480</pre></div>
481There are two different ways to accomplish this. Unfortunately, judging
482from customer feedback as well from common sense, both do not work very well
483with a messed up local DNS (including /etc/hosts files) and/or
484&uuml;berparanoid or misconfigured firewalls (in case of connections
485across one).
486<ul>
487 <li>
488 <p>
489 <i>First method: Determine client name on client, and
490 try to cross-check on server</i>
491 <p>
492 <p>
493 This does not work for a number of people because (1) the
494 <tt>/etc/hosts</tt> file on the client machine has errors
495 (yes, there are plenty machines with a completely
496 messed up <tt>/etc/hosts</tt> file), (2) the
497 server cannot resolve the client address because the local DNS is
498 f***ed up, or (3) the client machine has multiple network interfaces, and
499 the interface used is not the one the client name resolves to.
500 </p>
501 <p>
502 If the client uses the wrong interface on a multi-interface machine,
503 there is a config file option
504 <tt>SetBindAddress=</tt><i>IP address</i>
505 that allows to choose the interface the client will use for
506 outgoing connections.
507 </p>
508 <p>
509 If you want to download the config file from the server, you
510 should instead use the corresponding command line
511 <tt>--bind-address=</tt><i>IP address</i>
512 to select the interface.
513 </p>
514
515 <p>
516 If you encounter problems, you may (1) fix your
517 <tt>/etc/hosts</tt> file(s), (2) fix your local DNS, or
518 (3) switch to the second method.
519 </p>
520 <p>
521 Errors in name resolving/cross-checking can be avoided by setting a
522 very low severity (lower than the logging threshold), e.g.
523 </p>
524 <p>
525 <tt>SeverityLookup=</tt><i>debug</i>
526 </p>
527 <p>
528 in the <i>Misc</i> section of the server configuration,
529 if you prefer running <i>unsafe</i> at any speed
530 instead of fixing the problem (you have been warned). Doing so will
531 allow an attacker to pose as the client.
532 </p>
533 </li>
534 <li>
535 <p><i>Second method: Use address of connecting entity as
536 known to the communication layer</i></p>
537 <p>
538 This has been dropped as default
539 long ago because it may not always be the
540 address of the client machine.
541 To enable this method, use
542 </p>
543 <p>
544 <tt>SetClientFromAccept=</tt><i>true</i>
545 </p>
546 <p>
547 in the <i>Misc</i> section of the server configuration
548 file. If the address cannot be resolved, or reverse lookup of the
549 resolved name fails, <i>no</i> error message will be issued,
550 but the numerical address will be used.
551 </p>
552 </li>
553</ul><br><br></dd>
554<dt><b><a name="Client/Server4">4.5. Cannot resolve socket peer IP for client host=XXX peer=YYY</a></b></dt>
555<dd>See above<br><br></dd>
556<dt><b><a name="Client/Server5">4.6. Reverse lookup of socket peer failed host=XXX peer=YYY obj=ZZZ</a></b></dt>
557<dd>See above<br><br></dd>
558<dt><b><a name="Client/Server6">4.7. No socket peer alias matches client name host=XXX peer=YYY</a></b></dt>
559<dd>See above<br><br></dd>
560<dt><b><a name="Client/Server7">4.8. Session key negotiation failed</a></b></dt>
561<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
562<dt><b><a name="Client/Server8">4.9. Invalid connection attempt: Not in client list</a></b></dt>
563<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
564<dt><b><a name="Client/Server9">4.10. Invalid connection attempt: Session key mismatch</a></b></dt>
565<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
566<dt><b><a name="Client/Server10">4.11. How do I update the file signature database ?</a></b></dt>
567<dd>If you keep the file signature database on the server,
568 the database is supposed to be updated on the server, using the
569 <a href="http://www.la-samhna.de/beltane/">beltane</a>
570 web-based console (currently in beta) and the
571 log messages from the client.
572 <p>
573 Alternatively, you can <code>scp</code> the database
574 to the client, run <code>samhain -t update -l none</code> (you
575 need to avoid logging because otherwise you will get in conflict with
576 the running samhain daemon), and then <code>scp</code> the
577 database back to the server. Actually, with a properly set up
578 &quot;ssh&quot;, using RSA/DSA authentication
579 and ssh-agent you could write a script to automate this.<br><br></dd>
580<dt><b><a name="Client/Server11">4.12. Time limit exceeded</a></b></dt>
581<dd>The respective client for that this message is generated has not
582 sent anything for some interval of time (default 84600 sec = 1 day).
583 The interval can be set as follows:
584<div class="block"><pre>
585 [Misc]
586 # unit is seconds
587 SetClientTimeLimit=NNN
588</pre></div>
589
590 This feature has the purpose to detect if a client is dead. You
591 might want to ensure that timestamps are sent to the server:
592<div class="block"><pre>
593 [Log]
594 ExportSeverity=mark
595</pre></div>
596 If you don't want to use this feature, set the time limit to some
597 very large value.<br><br></dd>
598<dt><b><a name="Client/Server12">4.13. Invalid connection attempt: Signature mismatch</a></b></dt>
599<dd>Clients sign their messages using a session key negotiated
600 with the server. The message indicates that the server could
601 not verify the signature. This may be caused by a running two
602 instances of samhain on the same client machine, both of them
603 accessing the server (and negotiating different session keys
604 ...). The system will recover automatically from the problem
605 by forcing the failed client to negotiate a fresh session key.<br><br></dd>
606<dt><b><a name="Client/Server13">4.14. [Server] PANIC .. Address already in use&nbsp; &nbsp;subroutine=bind</a></b></dt>
607<dd>The server cannot bind to its port because the port is already used.
608 Maybe you have accidentially already an instance of the
609 server running.<br><br></dd>
610</dl>
611<hr><h2>5. Email</h2>
612<dl>
613<dt><b><a name="Email0">5.1. Reverse lookup failed</a></b></dt>
614<dd>Fix your DNS (reverse lookup: numerical IP address to FQDN, to verify
615 FQDN to numerical IP address).
616<div class="block"><pre>
617Whether &quot;nslookup&quot; works is not very informative, because
618&quot;nslookup&quot; does not use the resolver library of the operating
619system. Therefore,
620it is not exactly the
621best tool for debugging name resolving problems (see the book
622&quot;DNS and bind&quot;).
623</pre></div><br><br></dd>
624<dt><b><a name="Email1">5.2. From daemon@example.com</a></b></dt>
625<dd>samhain fails to resolve the
626 self-address of the host.
627See 'Client cannot self-resolve' in the 'Most frequently' section.<br><br></dd>
628<dt><b><a name="Email2">5.3. How do I define more than one email addresses ?</a></b></dt>
629<dd>Use <tt>SetMailAddress=...</tt> multiple times (upt to eight addresses
630are possible, with at most 63 characters per address):
631<div class="block"><pre>
632[Misc]
633SetMailAddress=aaa@foo.com
634SetMailAddress=bbb@foo.com
635</pre></div><br><br></dd>
636</dl>
637<hr><h2>6. Misc</h2>
638<dl>
639<dt><b><a name="Misc0">6.1. Error message: &quot;Invalid line XYZ in configuration file&quot;</a></b></dt>
640<dd>This message indicates that line XYZ in the configuration file contains
641an unrecognized directive. The primary reasons are:<br />
642
643(a) The directive should be placed into a particular section of the
644configuration file, but the section header is not present (or you forgot
645to uncomment it).<br />
646
647(b) Samhain is compiled without support for this directive.<br />
648
649(c) You have a typo in the directive.<br /><br><br></dd>
650<dt><b><a name="Misc1">6.2. Why do I get a local logfile if I log to the server ?</a></b></dt>
651<dd>Because you can use all log facilities in parallel. You should
652 switch off in the config file what you don't want/need:
653<div class="block"><pre>
654 [Log]
655 # local log file
656 LogSeverity=none
657</pre></div><br><br></dd>
658<dt><b><a name="Misc2">6.3. Why is there no NIS support with a static samhain executable on Linux ?</a></b></dt>
659<dd>Some functions (including NIS) require
660 libraries that are only available as shared libraries
661 with modern GLIBC versions. While you can always compile a static
662 executable, normally it would still open the shared library at runtime.
663 As of version 1.8.11, samhain avoids this by providing replacement
664 functions from uClibc. However, these do not include NIS support.<br><br></dd>
665<dt><b><a name="Misc3">6.4. Why do I get hundreds of messages about modified CTIME ?</a></b></dt>
666<dd>This happens because some
667 backup applications reset the atime/mtime timestamps, which causes
668 the ctime timestamp to be modified (rootkits avoid this by
669 temporarily resetting the system clock to the original ctime ...).
670 <p>
671 To fix this problem, read the manual of your backup application, or
672 redefine the ReadOnly policy to <i>not</i> check
673 the ctime timestamp:
674<div class="block"><pre>
675 [Misc]
676 RedefReadOnly=-CTM
677</pre></div>
678<div class="warnblock"><pre>
679 Order matters - you must <i>first</i> redefine
680 ReadOnly <i>before</i> you use it
681</pre></div><br><br></dd>
682<dt><b><a name="Misc4">6.5. PANIC &mdash; File not accessible</a></b></dt>
683<dd>Most likely permission denied because of unsufficient privileges.<br><br></dd>
684<dt><b><a name="Misc5">6.6. How can I avoid error messages for invalid UIDs (no such user) ?</a></b></dt>
685<dd>Set SeverityNames to a low value
686<div class="block"><pre>
687[EventSeverity]
688SeverityNames=debug
689</pre></div><br><br></dd>
690<dt><b><a name="Misc6">6.7. [Redhat] The /etc/init.d/(samhain|yule) init script hangs</a></b></dt>
691<dd>Redhat uses &quot;initlog&quot; (see
692 <code>man initlog</code>) in initscripts. If it hangs, most probably
693 samhain/yule runs in the foreground rather than as daemon. Set
694 daemon mode in the configuration file:
695<div class="block"><pre>
696[Misc]
697Daemon=yes
698</pre></div><br><br></dd>
699<dt><b><a name="Misc7">6.8. The /etc/init.d/(samhain|yule) init script exits with: execvp: No such file or directory</a></b></dt>
700<dd>Either the program is not installed, or it is not in the PATH (the one
701 used by the init script, which may be different from your PATH).<br><br></dd>
702<dt><b><a name="Misc8">6.9. Why am I not receiving the &quot;BEGIN LOGKEY&quot; message by email ?</a></b></dt>
703<dd>This message (which contains the key to verify the log file) is generated
704 when logging to the log file starts. It has the severity &quot;ALRT&quot;,
705 thus you should make sure that you have set the logging threshold for
706 email correctly to receive it.<br><br></dd>
707<dt><b><a name="Misc9">6.10. Why does console logging fail if I compile with
708 <code>--enable-(micro-)stealth</code> ?</a></b></dt>
709<dd>The default logging options are more &quot;stealthy&quot;. Set the
710 threshold explicitely rather than relying on the default.<br><br></dd>
711<dt><b><a name="Misc10">6.11. I need a list for my schedule !</a></b></dt>
712<dd>You can have the same effect with a list of schedules. See the section
713&quot;Timing file checks&quot; in the manual.<br><br></dd>
714<dt><b><a name="Misc11">6.12. The hiding kernel module has no effect !</a></b></dt>
715<dd>Most probably you compiled using the wrong &quot;System.map&quot; file.<br><br></dd>
716<dt><b><a name="Misc12">6.13. What does the message &quot;Large lstat/open overhead&quot; mean ?</a></b></dt>
717<dd>Your system needs several seconds to proceed from an lstat() system call
718 to an open() system call. This is a tremenduous overhead, and
719 indicates that either your system has a really severe performance problem,
720 or someone tries to slow down samhain.<br><br></dd>
721<dt><b><a name="Misc13">6.14. What does the message &quot;Device not available path=/dev/random&quot; mean ? I have /dev/random !</a></b></dt>
722<dd>/dev/random blocks unless there is some entropy it can deliver. Samhain
723 will time out and fall back on /dev/urandom after some seconds to avoid
724 hanging for a potentially long time. It will try /dev/random again next
725 time it needs entropy.<br><br></dd>
726<dt><b><a name="Misc14">6.15. Logging to an external program fails; the program receives no data
727 on stdin !</a></b></dt>
728<dd>Probably your program is not designed to <i>wait for input</i>, but exits
729 if reading fails (because there is no data <i>yet</i>). You may want to
730 let your program wait for the terminating &quot;[EOF]&quot; line.<br><br></dd>
731<dt><b><a name="Misc15">6.16. SIGILL on AIX</a></b></dt>
732<dd>For each scanned file, samhain needs to
733 store some information in memory (e.g. to recognize changes that have
734 already been reported, and avoid duplicate reports). On AIX, if you are
735 checking a <i>really huge</i> number of files,
736 memory usage may exceed the default limit of 256 MB, and the process may
737 terminate with SIGILL.
738 <p>
739 The problem can be solved by linking with the flag
740 <code>-bmaxdata:0x80000000</code>. This allows the application to
741 access up to 8 segments (where each segment is 256MB).
742 <p>
743 If you are using gcc, you need to use instead
744 the flag <code>-Wl,bmaxdata:0x80000000</code>, which tells
745 gcc to pass on the
746 <i>bmaxdata</i>
747 flag to the AIX linker. You can use the LDFLAGS environment variable to
748 pass linker flags to the configure script:
749<div class="block"><pre>
750 export LDFLAGS="-Wl,bmaxdata:0x80000000"
751</pre></div><br><br></dd>
752</dl>
753<hr><h2>7. Database</h2>
754<dl>
755<dt><b><a name="Database0">7.1. Why are client messages corrupted / incompletely stored in the DB ?</a></b></dt>
756<dd>Because the messages are not in XML format, and therefore incorrectly
757 parsed. The most frequent reasons are:
758<div class="block"><pre>
759 1.) Your server is compiled with --enable-xml-log, but your client(s)
760 is/are not.
761
762 2.) In your client or server configuration file, you are using
[19]763 the option for a custom message header, but without paying attention
[1]764 to preserving the XML format.
765</pre></div><br><br></dd>
766<dt><b><a name="Database1">7.2. I want / don't want the server timestamps (for client messages) in the SQL database</a></b></dt>
767<dd><div class="block"><pre>
768[Database]
769SetDBServerTstamp = true/false
770</pre></div>
771
772 This will enable/disable logging of the server timestamp for client
773 messages. The server timestamp will be written to a seperate record,
774 with <i>log_ref</i> set to the value of
775 <i>log_index</i> of the corresponding client message.<br><br></dd>
776<dt><b><a name="Database2">7.3. I don't want the client TIMESTAMP messages in the SQL database</a></b></dt>
777<dd><div class="block"><pre>
778 Sending timestamps from the client allows the server to detect if
779 a client is not running anymore (use SetClientTimeLimit=NNN in the
780 [Misc] section of the server config file to set the number of seconds
781 after which the server will issue an error message if no timestamp has
782 been received).
783</pre></div>
784
785 However, you might not want to log these timestamps to the database
786 (or other log facilities). To filter them, you can use two methods
787 (examples are for the SQL database).
788 The first
789 one has the disadvantage that only messages of
790 severity <i>err</i> or higher will be logged:
791<div class="block"><pre>
792 [Misc]
793 UseClientSeverity=yes
794
795 [Log]
796 DatabaseSeverity=err
797</pre></div>
798
799 The second method is more specific &mdash; log everything not
800 belonging to the STAMP class of messages:
801<div class="block"><pre>
802 [Misc]
803 UseClientClass=yes
804
805 [Log]
806 DatabaseClass=PANIC RUN FIL TCP ERR ENET EINPUT
807</pre></div><br><br></dd>
808<dt><b><a name="Database3">7.4. What does the log_ref field mean ?</a></b></dt>
809<dd>NULL are client messages. Nonzero integer is a server timestamp
810 for a client message (where log_ref indicates the log_index entry
811 number of the corresponding client message). Zero indicates a message
812 by the server itself (e.g. the server's start message).<br><br></dd>
[19]813<dt><b><a name="Database4">7.5. How can I check what is in the database ?</a></b></dt>
814<dd>Use a command line client to login to the database and query it:
815<div class="block"><pre>
816 sh$ mysql -u &lt;user_name&gt; -p &lt;database_name&gt;
817 Enter password: ****
818 mysql&gt; SELECT log_index,log_ref,log_host,log_sev,log_msg,path FROM &lt;table_name&gt; WHERE entry_status = 'NEW' ORDER BY log_index;
819 ....
820 mysql&gt; \q
821</pre></div><br><br></dd>
[1]822</dl>
823<hr>
824
825<p>Copyright (c) 2004 Rainer Wichmann</p>
826
827<p><i>This list of questions and answers was generated by
828<a href="http://www.makefaq.org/">makefaq</a>.</i>
829
830</div>
831</body>
832</html>
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