source: branches/samhain-2_2-branch/docs/FAQ.html@ 66

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Fix for MacOX X problems and Cygwin compile problem, resolves tickets #33, #34, #35.

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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>
131<p><i>FAQ Revised: Monday 11 September 2006 22:18:54</i></p>
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>
151<li><a href="#Build and install8">2.9. What is sh_tiger1.s?</a></li>
152<li><a href="#Build and install9">2.10. Why does static compiling (<code>--enable-static</code>) on MaxOS X fail ?</a></li>
153</ul></dd>
154<dt><b>3. File checking</b></dt>
155<dd><ul>
156<li><a href="#File checking0">3.1. How can I exclude a (sub-)directory ?</a></li>
157<li><a href="#File checking1">3.2. In messages about policy violations, what does the code after POLICY [XYZ]
158mean ?</a></li>
159<li><a href="#File checking2">3.3. Does samhain support prelink ?</a></li>
160<li><a href="#File checking3">3.4. I get error messages about 'subdirectory count != hardlinks'</a></li>
161</ul></dd>
162<dt><b>4. Client/Server</b></dt>
163<dd><ul>
164<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>
165<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>
166<li><a href="#Client/Server2">4.3. The server wants to send rc.ip-adress rather than rc.fqdn to the client</a></li>
167<li><a href="#Client/Server3">4.4. Cannot resolve client name host=XXX</a></li>
168<li><a href="#Client/Server4">4.5. Cannot resolve socket peer IP for client host=XXX peer=YYY</a></li>
169<li><a href="#Client/Server5">4.6. Reverse lookup of socket peer failed host=XXX peer=YYY obj=ZZZ</a></li>
170<li><a href="#Client/Server6">4.7. No socket peer alias matches client name host=XXX peer=YYY</a></li>
171<li><a href="#Client/Server7">4.8. Session key negotiation failed</a></li>
172<li><a href="#Client/Server8">4.9. Invalid connection attempt: Not in client list</a></li>
173<li><a href="#Client/Server9">4.10. Invalid connection attempt: Session key mismatch</a></li>
174<li><a href="#Client/Server10">4.11. How do I update the file signature database ?</a></li>
175<li><a href="#Client/Server11">4.12. Time limit exceeded</a></li>
176<li><a href="#Client/Server12">4.13. Invalid connection attempt: Signature mismatch</a></li>
177<li><a href="#Client/Server13">4.14. [Server] PANIC .. Address already in use&nbsp; &nbsp;subroutine=bind</a></li>
178</ul></dd>
179<dt><b>5. Email</b></dt>
180<dd><ul>
181<li><a href="#Email0">5.1. Reverse lookup failed</a></li>
182<li><a href="#Email1">5.2. From daemon@example.com</a></li>
183<li><a href="#Email2">5.3. How do I define more than one email addresses ?</a></li>
184</ul></dd>
185<dt><b>6. Misc</b></dt>
186<dd><ul>
187<li><a href="#Misc0">6.1. Error message: &quot;Invalid line XYZ in configuration file&quot;</a></li>
188<li><a href="#Misc1">6.2. Why do I get a local logfile if I log to the server ?</a></li>
189<li><a href="#Misc2">6.3. Why is there no NIS support with a static samhain executable on Linux ?</a></li>
190<li><a href="#Misc3">6.4. Why do I get hundreds of messages about modified CTIME ?</a></li>
191<li><a href="#Misc4">6.5. PANIC &mdash; File not accessible</a></li>
192<li><a href="#Misc5">6.6. How can I avoid error messages for invalid UIDs (no such user) ?</a></li>
193<li><a href="#Misc6">6.7. [Redhat] The /etc/init.d/(samhain|yule) init script hangs</a></li>
194<li><a href="#Misc7">6.8. The /etc/init.d/(samhain|yule) init script exits with: execvp: No such file or directory</a></li>
195<li><a href="#Misc8">6.9. Why am I not receiving the &quot;BEGIN LOGKEY&quot; message by email ?</a></li>
196<li><a href="#Misc9">6.10. Why does console logging fail if I compile with
197 <code>--enable-(micro-)stealth</code> ?</a></li>
198<li><a href="#Misc10">6.11. I need a list for my schedule !</a></li>
199<li><a href="#Misc11">6.12. The hiding kernel module has no effect !</a></li>
200<li><a href="#Misc12">6.13. What does the message &quot;Large lstat/open overhead&quot; mean ?</a></li>
201<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>
202<li><a href="#Misc14">6.15. Logging to an external program fails; the program receives no data
203 on stdin !</a></li>
204<li><a href="#Misc15">6.16. SIGILL on AIX</a></li>
205</ul></dd>
206<dt><b>7. Database</b></dt>
207<dd><ul>
208<li><a href="#Database0">7.1. Why are client messages corrupted / incompletely stored in the DB ?</a></li>
209<li><a href="#Database1">7.2. I want / don't want the server timestamps (for client messages) in the SQL database</a></li>
210<li><a href="#Database2">7.3. I don't want the client TIMESTAMP messages in the SQL database</a></li>
211<li><a href="#Database3">7.4. What does the log_ref field mean ?</a></li>
212<li><a href="#Database4">7.5. How can I check what is in the database ?</a></li>
213</ul></dd>
214</dl>
215<hr><h2>1. Most frequently</h2>
216<dl>
217<dt><b><a name="Most frequently0">1.1. Owner not trustworthy / Group writeable and member not trustworthy</a></b></dt>
218<dd>An untrusted user (might be an untrusted group member
219 for group writeable files/directories) owns or can write to an
220 element in the path listed in the error message. This concerns
221 the configuration file, the log file, and the database file.
222 The offending element in the path is identified as obj=/xxx in the
223 error message.
224 To fix the problem, see next entry.<br><br></dd>
225<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>
226<dd>Paths to critical
227 files (e.g. the configuration file) must be writeable by trusted users
228 only.
229 If a path element is group writeable, all group members must be trusted.
230 By default, only <i>root</i> and the (effective) <i>user</i> of
231 the program are trusted. To add trusted users, use the compile time
232 option
233<div class="block"><pre>
234$ ./configure --with-trusted=0,...
235</pre></div>
236 or the configure file option:
237<div class="block"><pre>
238[Misc]
239TrustedUser=username
240</pre></div>
241If the path to the configuration file itself is writeable
242 by other users than <i>root</i> and the
243 <i>effective user</i>
244 these must be defined as trusted already
245 at compile time.<br><br></dd>
246<dt><b><a name="Most frequently2">1.3. It does not log anything / Can't stop logging to console</a></b></dt>
247<dd>(1) There is a section in the manual dealing with
248logging and filtering.<br />
249
250(2) To log to the console:
251<div class="block"><pre>
252$ samhain -p info ...
253</pre></div>
254or in the configuration file:
255<div class="block"><pre>
256[Log]
257PrintSeverity=info
258</pre></div>
259
260To <i>stop</i> logging to the console:
261<div class="block"><pre>
262$ samhain -p none ...
263</pre></div>
264or in the configuration file:
265<div class="block"><pre>
266[Log]
267PrintSeverity=none
268</pre></div>
269Defining <tt>/dev/null</tt> as console device works as well, but
270is a bad idea, because samhain will open the device and write (i.e. it is
271a very inefficient method).<br><br></dd>
272<dt><b><a name="Most frequently3">1.4. Client cannot self-resolve, but nslookup works fine</a></b></dt>
273<dd><ul>
274<li>Nslookup is a program to query Internet domain name servers.
275</li>
276<li>Applications (like samhain) are not supposed to query DNS servers
277 directly. Rather, they are supposed to query the resolver library that:
278 <ul>
279 <li>is provided by the operating system,</li>
280 <li>configured by the system administrator,</li>
281 <li>may use several different method to determine host names, as
282 configured in <tt>/etc/nsswitch.conf</tt>, and</li>
283 <li>usually is configured to give precedence to
284 the <tt>/etc/hosts</tt> file.</li>
285 </ul>
286</li>
287<li>Therefore, whether nslookup gives correct answers may be completely
288 irrelevant. For self-resolving the own hostname, the resolver
289 library probably will use <tt>/etc/hosts</tt>, rather than
290 querying a DNS server.
291</li>
292</ul>
293<p>
294Below you can find some examples of good and bad <tt>/etc/hosts</tt> files:
295</p>
296<div class="block"><pre>
297 # CORRECT
298 #
299 127.0.0.1 localhost
300 xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
301</pre></div>
302
303<div class="block"><pre>
304 # CORRECT
305 #
306 127.0.0.1 localhost.localdomain localhost
307 xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
308</pre></div>
309
310<div class="block"><pre>
311 # BAD
312 #
313 127.0.0.1 myhost.mydomain.tld localhost
314 xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
315</pre></div>
316
317<div class="block"><pre>
318 # BAD
319 #
320 127.0.0.1 localhost myhost
321 xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
322</pre></div><br><br></dd>
323</dl>
324<hr><h2>2. Build and install</h2>
325<dl>
326<dt><b><a name="Build and install0">2.1. [Fedora Core] Cannot compile with --enable-khide</a></b></dt>
327<dd>The Fedora Core kernel is patched to unconditionally deny reading
328from /dev/kmem. Compiling the stealth kernel modules is not possible
329under these circumstances.<br><br></dd>
330<dt><b><a name="Build and install1">2.2. [Fedora Core] Cannot compile with --with-kcheck</a></b></dt>
331<dd>The Fedora Core kernel is patched to unconditionally deny reading
332from /dev/kmem. Checking the kernel for the presence of rootkits is
333not possible under these circumstances.<br><br></dd>
334<dt><b><a name="Build and install2">2.3. &quot;make&quot; loops infinitely !</a></b></dt>
335<dd>This may happen (e.g. when building via NFS for multiple architectures)
336 if the relative timestamps in the source directory are
337 wrong (time not in sync on different machines) or some intermediate
338 target is unusable (up-to-date, but built for a different OS). Use
339 &quot;touch * &amp;&amp; make distclean&quot; in the source directory
340 to recover.<br><br></dd>
341<dt><b><a name="Build and install3">2.4. Why does static compiling (<code>--enable-static</code>) on Solaris fail ?</a></b></dt>
342<dd>Ingo Rogalsky has provided the following information: It isn't possible
343 to link Samhain statically with Solaris. This
344 is a Solaris issue (see Sun Infodoc ID12624) and not a samhain problem.<br><br></dd>
345<dt><b><a name="Build and install4">2.5. Compilation fails with '/usr/bin/ld: cannot find -lnss_files'</a></b></dt>
346<dd>For Linux, this is a known problem with --enable-static if you compile
347 in MySQL support. The problem is that the
348 <tt>mysql_config</tt> that comes as part of the MySQL
349 distribution script incorrectly lists dependencies on
350 the libnss_files and libnss_dns libraries which are only available as
351 shared libraries, so the linker cannot find the static libraries.
352
353 You can check this by inspecting the output of
354 <code>mysql_config --libs</code>. The version of
355 <tt>mysql_config</tt> that comes with the RedHat mysql
356 RPM (RedHat 9) does not have this bug; the one distributed by the MySQL
357 people has. You can fix the problem by editing
358 <tt>mysql_config</tt>: search for the
359 <i>client_libs</i> variable, and remove all instances
360 of <i>-lnss_files</i> and <i>-lnss_dns</i>.<br><br></dd>
361<dt><b><a name="Build and install5">2.6. The executable is corrupted after installation</a></b></dt>
362<dd>The executable will get stripped during the installation. On
363 suitable systems (i386 Linux/FreeBSD currently), additionally
364 the &quot;sstrip&quot;
365 utility (copyright 1999 by Brian Raiter, under the GNU GPL)
366 will be used to strip the executable even more, to prevent
367 debugging with the GNU &quot;gdb&quot; debugger.
368 The &quot;strip&quot; utility cannot handle the resulting
369 executable, therefore trying to strip manually after installation
370 will corrupt the executable.<br><br></dd>
371<dt><b><a name="Build and install6">2.7. --enable-xml-log has no effect</a></b></dt>
372<dd>If you have compiled for stealth, you won't see much, because if
373 obfuscated, then both a 'normal' and an XML logfile look,
374 well ... obfuscated. Use <code>samhain -jL /path/to/logfile</code>
375 to view the logfile.<br><br></dd>
376<dt><b><a name="Build and install7">2.8. ./install-sh: strip: not found (Solaris)</a></b></dt>
377<dd>Install the SUNWbtool package.<br><br></dd>
378<dt><b><a name="Build and install8">2.9. What is sh_tiger1.s?</a></b></dt>
379<dd>This is a precompiled assembly file for the i386 architecture
380generated from sh_tiger1.c using gcc 3.4.0 with the following options,
381that were found to generate the fastest code:
382<pre>
383 -O1 -fno-delayed-branch -fexpensive-optimizations -fstrength-reduce
384 -fpeephole2 -fschedule-insns2 -fregmove -frename-registers -fweb
385 -momit-leaf-frame-pointer -funroll-loops
386</pre>
387These options were determined using
388<a href="http://www.coyotegulch.com/products/acovea/">acovea</a> 5.1.1
389by Scott Robert Ladd. The file is provided as precompiled assembly
390because different versions of gcc can have very different performance,
391require different options to compile optimal code, and
392it would be impossible to maintain a library of optimal compile options
393for every version of gcc.<br><br></dd>
394<dt><b><a name="Build and install9">2.10. Why does static compiling (<code>--enable-static</code>) on MaxOS X fail ?</a></b></dt>
395<dd>Static linking is not supported on MacOS X, see
396<a href="http://developer.apple.com/qa/qa2001/qa1118.html">Technical Q&A QA1118</a>.
397This is a MacOS X issue and not a bug in samhain.<br><br></dd>
398</dl>
399<hr><h2>3. File checking</h2>
400<dl>
401<dt><b><a name="File checking0">3.1. How can I exclude a (sub-)directory ?</a></b></dt>
402<dd><div class="block"><pre>
403[IgnoreAll]
404dir=-1/ignore/this/subdirectory
405</pre></div><br><br></dd>
406<dt><b><a name="File checking1">3.2. In messages about policy violations, what does the code after POLICY [XYZ]
407mean ?</a></b></dt>
408<dd>This code indicates which items are modified (e.g. C = checksum). You can
409find a description in section 5.4.9 in the user manual. It is there because
410then you can see in the message list of the Beltane web console what has been
411modified, without the need to look at the message in detail.<br><br></dd>
412<dt><b><a name="File checking2">3.3. Does samhain support prelink ?</a></b></dt>
413<dd>Yes. There is a special checking policy [Prelink]. Directories with
414prelinked executables / shared libraries (see /etc/prelink.conf) should be
415placed under this policy, rather than under the [ReadOnly] policy.<br><br></dd>
416<dt><b><a name="File checking3">3.4. I get error messages about 'subdirectory count != hardlinks'</a></b></dt>
417<dd>Some filesystems do not always follow the rule that the number
418of directory
419hardlinks equals the number of subdirectories. E.g. the root directory of
420reiserfs partitions generally seems to have two additional hardlinks.
421To account for such exceptions, you can either switch off the
422hardlink check globally, or specify exceptions:
423<div class="block"><pre>
424[Misc]
425# Switch off hardlink check
426#
427UseHardlinkCheck=no
428</pre></div>
429<div class="block"><pre>
430[Misc]
431# Specify exceptions for the hardlink check
432#
433HardlinkOffset=N:/path
434</pre></div>
435Here, N is the numerical offset (actual - expected hardlinks) for
436'/path'. For multiple exceptions, use
437this options multiple times (note that '/path N:/path2' would itself be a valid
438path, so using the option only once with multiple exceptions on the same line
439would be ambiguous).<br><br></dd>
440</dl>
441<hr><h2>4. Client/Server</h2>
442<dl>
443<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>
444<dd>Pat Smith has posted the following solution. On the client, create
445an iptable rule as follows (<i>note: you probably don't need this if you
446configure / compile in 127.0.0.1 as the server address</i>):
447<div class="block"><pre>
448iptables -t nat -A OUTPUT -p tcp -m tcp --dport 49777 -d <i>server-ip</i> -j REDIRECT
449</pre></div>
450
451On the server, create an ssh tunnel for each client outside the firewall:
452
453<div class="block"><pre>
454ssh -f -C -R 49777:localhost:49777 -N <i>client-ip</i>
455</pre></div>
456
457It is necessary that each client has a distinct name, and that the server
458knows the name of the client. With the setup above, each client will appear
459as &quot;localhost&quot; to the server, thus the server
460needs to trust the client name
461as reported by the client itself, and suppress all eroors on resolving
462this name to the apparent address. In the server configuration:
463
464<div class="block"><pre>
465[Misc]
466SetClientFromAccept = false
467SeverityLookup = debug
468</pre></div>
469
470Obviously, self-resolving must work on the client machine, otherwise
471you are in trouble (see next issue).<br><br></dd>
472<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>
473<dd>See 'Client cannot self-resolve' in the 'Most frequently' section<br><br></dd>
474<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>
475<dd>The client self-resolves to its ip address.
476See 'Client cannot self-resolve' in the 'Most frequently' section<br><br></dd>
477<dt><b><a name="Client/Server3">4.4. Cannot resolve client name host=XXX</a></b></dt>
478<dd><div class="block"><pre>
479The server must be able to determine the client name.
480This is because only authenticated connections from registered
481clients are allowed, and
482the server must be able to check the client hostname against the list of
483allowed hosts, and look up the password verifier for that
484host.
485</pre></div>
486There are two different ways to accomplish this. Unfortunately, judging
487from customer feedback as well from common sense, both do not work very well
488with a messed up local DNS (including /etc/hosts files) and/or
489&uuml;berparanoid or misconfigured firewalls (in case of connections
490across one).
491<ul>
492 <li>
493 <p>
494 <i>First method: Determine client name on client, and
495 try to cross-check on server</i>
496 <p>
497 <p>
498 This does not work for a number of people because (1) the
499 <tt>/etc/hosts</tt> file on the client machine has errors
500 (yes, there are plenty machines with a completely
501 messed up <tt>/etc/hosts</tt> file), (2) the
502 server cannot resolve the client address because the local DNS is
503 f***ed up, or (3) the client machine has multiple network interfaces, and
504 the interface used is not the one the client name resolves to.
505 </p>
506 <p>
507 If the client uses the wrong interface on a multi-interface machine,
508 there is a config file option
509 <tt>SetBindAddress=</tt><i>IP address</i>
510 that allows to choose the interface the client will use for
511 outgoing connections.
512 </p>
513 <p>
514 If you want to download the config file from the server, you
515 should instead use the corresponding command line
516 <tt>--bind-address=</tt><i>IP address</i>
517 to select the interface.
518 </p>
519
520 <p>
521 If you encounter problems, you may (1) fix your
522 <tt>/etc/hosts</tt> file(s), (2) fix your local DNS, or
523 (3) switch to the second method.
524 </p>
525 <p>
526 Errors in name resolving/cross-checking can be avoided by setting a
527 very low severity (lower than the logging threshold), e.g.
528 </p>
529 <p>
530 <tt>SeverityLookup=</tt><i>debug</i>
531 </p>
532 <p>
533 in the <i>Misc</i> section of the server configuration,
534 if you prefer running <i>unsafe</i> at any speed
535 instead of fixing the problem (you have been warned). Doing so will
536 allow an attacker to pose as the client.
537 </p>
538 </li>
539 <li>
540 <p><i>Second method: Use address of connecting entity as
541 known to the communication layer</i></p>
542 <p>
543 This has been dropped as default
544 long ago because it may not always be the
545 address of the client machine.
546 To enable this method, use
547 </p>
548 <p>
549 <tt>SetClientFromAccept=</tt><i>true</i>
550 </p>
551 <p>
552 in the <i>Misc</i> section of the server configuration
553 file. If the address cannot be resolved, or reverse lookup of the
554 resolved name fails, <i>no</i> error message will be issued,
555 but the numerical address will be used.
556 </p>
557 </li>
558</ul><br><br></dd>
559<dt><b><a name="Client/Server4">4.5. Cannot resolve socket peer IP for client host=XXX peer=YYY</a></b></dt>
560<dd>See above<br><br></dd>
561<dt><b><a name="Client/Server5">4.6. Reverse lookup of socket peer failed host=XXX peer=YYY obj=ZZZ</a></b></dt>
562<dd>See above<br><br></dd>
563<dt><b><a name="Client/Server6">4.7. No socket peer alias matches client name host=XXX peer=YYY</a></b></dt>
564<dd>See above<br><br></dd>
565<dt><b><a name="Client/Server7">4.8. Session key negotiation failed</a></b></dt>
566<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
567<dt><b><a name="Client/Server8">4.9. Invalid connection attempt: Not in client list</a></b></dt>
568<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
569<dt><b><a name="Client/Server9">4.10. Invalid connection attempt: Session key mismatch</a></b></dt>
570<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
571<dt><b><a name="Client/Server10">4.11. How do I update the file signature database ?</a></b></dt>
572<dd>If you keep the file signature database on the server,
573 the database is supposed to be updated on the server, using the
574 <a href="http://www.la-samhna.de/beltane/">beltane</a>
575 web-based console (currently in beta) and the
576 log messages from the client.
577 <p>
578 Alternatively, you can <code>scp</code> the database
579 to the client, run <code>samhain -t update -l none</code> (you
580 need to avoid logging because otherwise you will get in conflict with
581 the running samhain daemon), and then <code>scp</code> the
582 database back to the server. Actually, with a properly set up
583 &quot;ssh&quot;, using RSA/DSA authentication
584 and ssh-agent you could write a script to automate this.<br><br></dd>
585<dt><b><a name="Client/Server11">4.12. Time limit exceeded</a></b></dt>
586<dd>The respective client for that this message is generated has not
587 sent anything for some interval of time (default 84600 sec = 1 day).
588 The interval can be set as follows:
589<div class="block"><pre>
590 [Misc]
591 # unit is seconds
592 SetClientTimeLimit=NNN
593</pre></div>
594
595 This feature has the purpose to detect if a client is dead. You
596 might want to ensure that timestamps are sent to the server:
597<div class="block"><pre>
598 [Log]
599 ExportSeverity=mark
600</pre></div>
601 If you don't want to use this feature, set the time limit to some
602 very large value.<br><br></dd>
603<dt><b><a name="Client/Server12">4.13. Invalid connection attempt: Signature mismatch</a></b></dt>
604<dd>Clients sign their messages using a session key negotiated
605 with the server. The message indicates that the server could
606 not verify the signature. This may be caused by a running two
607 instances of samhain on the same client machine, both of them
608 accessing the server (and negotiating different session keys
609 ...). The system will recover automatically from the problem
610 by forcing the failed client to negotiate a fresh session key.<br><br></dd>
611<dt><b><a name="Client/Server13">4.14. [Server] PANIC .. Address already in use&nbsp; &nbsp;subroutine=bind</a></b></dt>
612<dd>The server cannot bind to its port because the port is already used.
613 Maybe you have accidentially already an instance of the
614 server running.<br><br></dd>
615</dl>
616<hr><h2>5. Email</h2>
617<dl>
618<dt><b><a name="Email0">5.1. Reverse lookup failed</a></b></dt>
619<dd>Fix your DNS (reverse lookup: numerical IP address to FQDN, to verify
620 FQDN to numerical IP address).
621<div class="block"><pre>
622Whether &quot;nslookup&quot; works is not very informative, because
623&quot;nslookup&quot; does not use the resolver library of the operating
624system. Therefore,
625it is not exactly the
626best tool for debugging name resolving problems (see the book
627&quot;DNS and bind&quot;).
628</pre></div><br><br></dd>
629<dt><b><a name="Email1">5.2. From daemon@example.com</a></b></dt>
630<dd>samhain fails to resolve the
631 self-address of the host.
632See 'Client cannot self-resolve' in the 'Most frequently' section.<br><br></dd>
633<dt><b><a name="Email2">5.3. How do I define more than one email addresses ?</a></b></dt>
634<dd>Use <tt>SetMailAddress=...</tt> multiple times (upt to eight addresses
635are possible, with at most 63 characters per address):
636<div class="block"><pre>
637[Misc]
638SetMailAddress=aaa@foo.com
639SetMailAddress=bbb@foo.com
640</pre></div><br><br></dd>
641</dl>
642<hr><h2>6. Misc</h2>
643<dl>
644<dt><b><a name="Misc0">6.1. Error message: &quot;Invalid line XYZ in configuration file&quot;</a></b></dt>
645<dd>This message indicates that line XYZ in the configuration file contains
646an unrecognized directive. The primary reasons are:<br />
647
648(a) The directive should be placed into a particular section of the
649configuration file, but the section header is not present (or you forgot
650to uncomment it).<br />
651
652(b) Samhain is compiled without support for this directive.<br />
653
654(c) You have a typo in the directive.<br /><br><br></dd>
655<dt><b><a name="Misc1">6.2. Why do I get a local logfile if I log to the server ?</a></b></dt>
656<dd>Because you can use all log facilities in parallel. You should
657 switch off in the config file what you don't want/need:
658<div class="block"><pre>
659 [Log]
660 # local log file
661 LogSeverity=none
662</pre></div><br><br></dd>
663<dt><b><a name="Misc2">6.3. Why is there no NIS support with a static samhain executable on Linux ?</a></b></dt>
664<dd>Some functions (including NIS) require
665 libraries that are only available as shared libraries
666 with modern GLIBC versions. While you can always compile a static
667 executable, normally it would still open the shared library at runtime.
668 As of version 1.8.11, samhain avoids this by providing replacement
669 functions from uClibc. However, these do not include NIS support.<br><br></dd>
670<dt><b><a name="Misc3">6.4. Why do I get hundreds of messages about modified CTIME ?</a></b></dt>
671<dd>This happens because some
672 backup applications reset the atime/mtime timestamps, which causes
673 the ctime timestamp to be modified (rootkits avoid this by
674 temporarily resetting the system clock to the original ctime ...).
675 <p>
676 To fix this problem, read the manual of your backup application, or
677 redefine the ReadOnly policy to <i>not</i> check
678 the ctime timestamp:
679<div class="block"><pre>
680 [Misc]
681 RedefReadOnly=-CTM
682</pre></div>
683<div class="warnblock"><pre>
684 Order matters - you must <i>first</i> redefine
685 ReadOnly <i>before</i> you use it
686</pre></div><br><br></dd>
687<dt><b><a name="Misc4">6.5. PANIC &mdash; File not accessible</a></b></dt>
688<dd>Most likely permission denied because of unsufficient privileges.<br><br></dd>
689<dt><b><a name="Misc5">6.6. How can I avoid error messages for invalid UIDs (no such user) ?</a></b></dt>
690<dd>Set SeverityNames to a low value
691<div class="block"><pre>
692[EventSeverity]
693SeverityNames=debug
694</pre></div><br><br></dd>
695<dt><b><a name="Misc6">6.7. [Redhat] The /etc/init.d/(samhain|yule) init script hangs</a></b></dt>
696<dd>Redhat uses &quot;initlog&quot; (see
697 <code>man initlog</code>) in initscripts. If it hangs, most probably
698 samhain/yule runs in the foreground rather than as daemon. Set
699 daemon mode in the configuration file:
700<div class="block"><pre>
701[Misc]
702Daemon=yes
703</pre></div><br><br></dd>
704<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>
705<dd>Either the program is not installed, or it is not in the PATH (the one
706 used by the init script, which may be different from your PATH).<br><br></dd>
707<dt><b><a name="Misc8">6.9. Why am I not receiving the &quot;BEGIN LOGKEY&quot; message by email ?</a></b></dt>
708<dd>This message (which contains the key to verify the log file) is generated
709 when logging to the log file starts. It has the severity &quot;ALRT&quot;,
710 thus you should make sure that you have set the logging threshold for
711 email correctly to receive it.<br><br></dd>
712<dt><b><a name="Misc9">6.10. Why does console logging fail if I compile with
713 <code>--enable-(micro-)stealth</code> ?</a></b></dt>
714<dd>The default logging options are more &quot;stealthy&quot;. Set the
715 threshold explicitely rather than relying on the default.<br><br></dd>
716<dt><b><a name="Misc10">6.11. I need a list for my schedule !</a></b></dt>
717<dd>You can have the same effect with a list of schedules. See the section
718&quot;Timing file checks&quot; in the manual.<br><br></dd>
719<dt><b><a name="Misc11">6.12. The hiding kernel module has no effect !</a></b></dt>
720<dd>Most probably you compiled using the wrong &quot;System.map&quot; file.<br><br></dd>
721<dt><b><a name="Misc12">6.13. What does the message &quot;Large lstat/open overhead&quot; mean ?</a></b></dt>
722<dd>Your system needs several seconds to proceed from an lstat() system call
723 to an open() system call. This is a tremenduous overhead, and
724 indicates that either your system has a really severe performance problem,
725 or someone tries to slow down samhain.<br><br></dd>
726<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>
727<dd>/dev/random blocks unless there is some entropy it can deliver. Samhain
728 will time out and fall back on /dev/urandom after some seconds to avoid
729 hanging for a potentially long time. It will try /dev/random again next
730 time it needs entropy.<br><br></dd>
731<dt><b><a name="Misc14">6.15. Logging to an external program fails; the program receives no data
732 on stdin !</a></b></dt>
733<dd>Probably your program is not designed to <i>wait for input</i>, but exits
734 if reading fails (because there is no data <i>yet</i>). You may want to
735 let your program wait for the terminating &quot;[EOF]&quot; line.<br><br></dd>
736<dt><b><a name="Misc15">6.16. SIGILL on AIX</a></b></dt>
737<dd>For each scanned file, samhain needs to
738 store some information in memory (e.g. to recognize changes that have
739 already been reported, and avoid duplicate reports). On AIX, if you are
740 checking a <i>really huge</i> number of files,
741 memory usage may exceed the default limit of 256 MB, and the process may
742 terminate with SIGILL.
743 <p>
744 The problem can be solved by linking with the flag
745 <code>-bmaxdata:0x80000000</code>. This allows the application to
746 access up to 8 segments (where each segment is 256MB).
747 <p>
748 If you are using gcc, you need to use instead
749 the flag <code>-Wl,bmaxdata:0x80000000</code>, which tells
750 gcc to pass on the
751 <i>bmaxdata</i>
752 flag to the AIX linker. You can use the LDFLAGS environment variable to
753 pass linker flags to the configure script:
754<div class="block"><pre>
755 export LDFLAGS="-Wl,bmaxdata:0x80000000"
756</pre></div><br><br></dd>
757</dl>
758<hr><h2>7. Database</h2>
759<dl>
760<dt><b><a name="Database0">7.1. Why are client messages corrupted / incompletely stored in the DB ?</a></b></dt>
761<dd>Because the messages are not in XML format, and therefore incorrectly
762 parsed. The most frequent reasons are:
763<div class="block"><pre>
764 1.) Your server is compiled with --enable-xml-log, but your client(s)
765 is/are not.
766
767 2.) In your client or server configuration file, you are using
768 the option for a custom message header, but without paying attention
769 to preserving the XML format.
770</pre></div><br><br></dd>
771<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>
772<dd><div class="block"><pre>
773[Database]
774SetDBServerTstamp = true/false
775</pre></div>
776
777 This will enable/disable logging of the server timestamp for client
778 messages. The server timestamp will be written to a seperate record,
779 with <i>log_ref</i> set to the value of
780 <i>log_index</i> of the corresponding client message.<br><br></dd>
781<dt><b><a name="Database2">7.3. I don't want the client TIMESTAMP messages in the SQL database</a></b></dt>
782<dd><div class="block"><pre>
783 Sending timestamps from the client allows the server to detect if
784 a client is not running anymore (use SetClientTimeLimit=NNN in the
785 [Misc] section of the server config file to set the number of seconds
786 after which the server will issue an error message if no timestamp has
787 been received).
788</pre></div>
789
790 However, you might not want to log these timestamps to the database
791 (or other log facilities). To filter them, you can use two methods
792 (examples are for the SQL database).
793 The first
794 one has the disadvantage that only messages of
795 severity <i>err</i> or higher will be logged:
796<div class="block"><pre>
797 [Misc]
798 UseClientSeverity=yes
799
800 [Log]
801 DatabaseSeverity=err
802</pre></div>
803
804 The second method is more specific &mdash; log everything not
805 belonging to the STAMP class of messages:
806<div class="block"><pre>
807 [Misc]
808 UseClientClass=yes
809
810 [Log]
811 DatabaseClass=PANIC RUN FIL TCP ERR ENET EINPUT
812</pre></div><br><br></dd>
813<dt><b><a name="Database3">7.4. What does the log_ref field mean ?</a></b></dt>
814<dd>NULL are client messages. Nonzero integer is a server timestamp
815 for a client message (where log_ref indicates the log_index entry
816 number of the corresponding client message). Zero indicates a message
817 by the server itself (e.g. the server's start message).<br><br></dd>
818<dt><b><a name="Database4">7.5. How can I check what is in the database ?</a></b></dt>
819<dd>Use a command line client to login to the database and query it:
820<div class="block"><pre>
821 sh$ mysql -u &lt;user_name&gt; -p &lt;database_name&gt;
822 Enter password: ****
823 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;
824 ....
825 mysql&gt; \q
826</pre></div><br><br></dd>
827</dl>
828<hr>
829
830<p>Copyright (c) 2004 Rainer Wichmann</p>
831
832<p><i>This list of questions and answers was generated by
833<a href="http://www.makefaq.org/">makefaq</a>.</i>
834
835</div>
836</body>
837</html>
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