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	3	<title>Frequently Asked Questions for Samhain</title>
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	122	<div class="body">
	123	<p style="text-align: center; background: #ccc; border: 1px solid #2d5588;"><a
	124	style="text-decoration: none;"
	125	href="http://www.la-samhna.de/samhain/">samhain file integrity
	126	scanner</a> \| <a style="text-decoration: none;"
	127	href="http://www.la-samhna.de/samhain/s_documentation.html">online
	128	documentation</a></p>
	129	<br><center><h1><a name="FAQ-top">Frequently Asked Questions for Samhain</a></h1></center>
	130	<br><center><h2>Rainer Wichmann</h2></center>
	131	<hr>
[91]	132	<div class="warnblock">
	133	<ul>
	134	<li>If you encounter problems after installing samhain, disable daemon
	135	mode and run it in the foreground with
	136	<tt>samhain --foreground [more options]</tt> for debugging.</li>
	137	<li>If you have problems getting client/server mode to work, please check
	138	the <a href="http://www.la-samhna.de/samhain/HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a> document.</li>
	139	</ul>
	140	</div>
[538]	141	<p><i>FAQ Revised: Monday 17 September 2018 15:13:17</i></p>
[1]	142	<hr><h2>Table of Contents</h2>
	143	<dl>
	144	<dt><b>1. Most frequently</b></dt>
	145	<dd><ul>
	146	<li><a href="#Most frequently0">1.1. Owner not trustworthy / Group writeable and member not trustworthy</a></li>
	147	<li><a href="#Most frequently1">1.2. samhain exits with the message "Untrusted path" for config/log/pid/database files</a></li>
	148	<li><a href="#Most frequently2">1.3. It does not log anything / Can't stop logging to console</a></li>
[538]	149	<li><a href="#Most frequently3">1.4. samhain exits with the message "Record with bad version number in file signature database"</a></li>
	150	<li><a href="#Most frequently4">1.5. Client cannot self-resolve, but nslookup works fine</a></li>
	151	<li><a href="#Most frequently5">1.6. Server logs hostname instead of FQDN (or vice versa)</a></li>
[1]	152	</ul></dd>
	153	<dt><b>2. Build and install</b></dt>
	154	<dd><ul>
[538]	155	<li><a href="#Build and install0">2.1. "make" loops infinitely !</a></li>
	156	<li><a href="#Build and install1">2.2. Why does static compiling (<code>--enable-static</code>) on Solaris fail ?</a></li>
	157	<li><a href="#Build and install2">2.3. Compilation fails with '/usr/bin/ld: cannot find -lnss_files'</a></li>
	158	<li><a href="#Build and install3">2.4. The executable is corrupted after installation</a></li>
	159	<li><a href="#Build and install4">2.5. --enable-xml-log has no effect</a></li>
	160	<li><a href="#Build and install5">2.6. ./install-sh: strip: not found (Solaris)</a></li>
	161	<li><a href="#Build and install6">2.7. What is sh_tiger1.s?</a></li>
	162	<li><a href="#Build and install7">2.8. Why does static compiling (<code>--enable-static</code>) on MaxOS X fail ?</a></li>
	163	<li><a href="#Build and install8">2.9. Why does compiling with MySQL fail on Solaris ?</a></li>
[1]	164	</ul></dd>
	165	<dt><b>3. File checking</b></dt>
	166	<dd><ul>
	167	<li><a href="#File checking0">3.1. How can I exclude a (sub-)directory ?</a></li>
	168	<li><a href="#File checking1">3.2. In messages about policy violations, what does the code after POLICY [XYZ]
	169	mean ?</a></li>
	170	<li><a href="#File checking2">3.3. Does samhain support prelink ?</a></li>
	171	<li><a href="#File checking3">3.4. I get error messages about 'subdirectory count != hardlinks'</a></li>
	172	</ul></dd>
	173	<dt><b>4. Client/Server</b></dt>
	174	<dd><ul>
	175	<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>
	176	<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>
	177	<li><a href="#Client/Server2">4.3. The server wants to send rc.ip-adress rather than rc.fqdn to the client</a></li>
	178	<li><a href="#Client/Server3">4.4. Cannot resolve client name host=XXX</a></li>
	179	<li><a href="#Client/Server4">4.5. Cannot resolve socket peer IP for client host=XXX peer=YYY</a></li>
	180	<li><a href="#Client/Server5">4.6. Reverse lookup of socket peer failed host=XXX peer=YYY obj=ZZZ</a></li>
	181	<li><a href="#Client/Server6">4.7. No socket peer alias matches client name host=XXX peer=YYY</a></li>
	182	<li><a href="#Client/Server7">4.8. Session key negotiation failed</a></li>
	183	<li><a href="#Client/Server8">4.9. Invalid connection attempt: Not in client list</a></li>
	184	<li><a href="#Client/Server9">4.10. Invalid connection attempt: Session key mismatch</a></li>
	185	<li><a href="#Client/Server10">4.11. How do I update the file signature database ?</a></li>
	186	<li><a href="#Client/Server11">4.12. Time limit exceeded</a></li>
	187	<li><a href="#Client/Server12">4.13. Invalid connection attempt: Signature mismatch</a></li>
	188	<li><a href="#Client/Server13">4.14. [Server] PANIC .. Address already in use   subroutine=bind</a></li>
	189	</ul></dd>
	190	<dt><b>5. Email</b></dt>
	191	<dd><ul>
	192	<li><a href="#Email0">5.1. Reverse lookup failed</a></li>
	193	<li><a href="#Email1">5.2. From daemon@example.com</a></li>
	194	<li><a href="#Email2">5.3. How do I define more than one email addresses ?</a></li>
	195	</ul></dd>
	196	<dt><b>6. Misc</b></dt>
	197	<dd><ul>
	198	<li><a href="#Misc0">6.1. Error message: "Invalid line XYZ in configuration file"</a></li>
	199	<li><a href="#Misc1">6.2. Why do I get a local logfile if I log to the server ?</a></li>
	200	<li><a href="#Misc2">6.3. Why is there no NIS support with a static samhain executable on Linux ?</a></li>
	201	<li><a href="#Misc3">6.4. Why do I get hundreds of messages about modified CTIME ?</a></li>
	202	<li><a href="#Misc4">6.5. PANIC — File not accessible</a></li>
	203	<li><a href="#Misc5">6.6. How can I avoid error messages for invalid UIDs (no such user) ?</a></li>
	204	<li><a href="#Misc6">6.7. [Redhat] The /etc/init.d/(samhain\|yule) init script hangs</a></li>
	205	<li><a href="#Misc7">6.8. The /etc/init.d/(samhain\|yule) init script exits with: execvp: No such file or directory</a></li>
	206	<li><a href="#Misc8">6.9. Why am I not receiving the "BEGIN LOGKEY" message by email ?</a></li>
	207	<li><a href="#Misc9">6.10. Why does console logging fail if I compile with
	208	<code>--enable-(micro-)stealth</code> ?</a></li>
	209	<li><a href="#Misc10">6.11. I need a list for my schedule !</a></li>
	210	<li><a href="#Misc11">6.12. The hiding kernel module has no effect !</a></li>
	211	<li><a href="#Misc12">6.13. What does the message "Large lstat/open overhead" mean ?</a></li>
	212	<li><a href="#Misc13">6.14. What does the message "Device not available path=/dev/random" mean ? I have /dev/random !</a></li>
	213	<li><a href="#Misc14">6.15. Logging to an external program fails; the program receives no data
	214	on stdin !</a></li>
	215	<li><a href="#Misc15">6.16. SIGILL on AIX</a></li>
	216	</ul></dd>
	217	<dt><b>7. Database</b></dt>
	218	<dd><ul>
	219	<li><a href="#Database0">7.1. Why are client messages corrupted / incompletely stored in the DB ?</a></li>
	220	<li><a href="#Database1">7.2. I want / don't want the server timestamps (for client messages) in the SQL database</a></li>
	221	<li><a href="#Database2">7.3. I don't want the client TIMESTAMP messages in the SQL database</a></li>
	222	<li><a href="#Database3">7.4. What does the log_ref field mean ?</a></li>
[19]	223	<li><a href="#Database4">7.5. How can I check what is in the database ?</a></li>
[1]	224	</ul></dd>
	225	</dl>
	226	<hr><h2>1. Most frequently</h2>
	227	<dl>
	228	<dt><b><a name="Most frequently0">1.1. Owner not trustworthy / Group writeable and member not trustworthy</a></b></dt>
	229	<dd>An untrusted user (might be an untrusted group member
	230	for group writeable files/directories) owns or can write to an
	231	element in the path listed in the error message. This concerns
	232	the configuration file, the log file, and the database file.
	233	The offending element in the path is identified as obj=/xxx in the
	234	error message.
	235	To fix the problem, see next entry.<br><br></dd>
	236	<dt><b><a name="Most frequently1">1.2. samhain exits with the message "Untrusted path" for config/log/pid/database files</a></b></dt>
	237	<dd>Paths to critical
	238	files (e.g. the configuration file) must be writeable by trusted users
	239	only.
	240	If a path element is group writeable, all group members must be trusted.
	241	By default, only <i>root</i> and the (effective) <i>user</i> of
	242	the program are trusted. To add trusted users, use the compile time
	243	option
	244	<div class="block"><pre>
	245	$ ./configure --with-trusted=0,...
	246	</pre></div>
	247	or the configure file option:
	248	<div class="block"><pre>
	249	[Misc]
	250	TrustedUser=username
	251	</pre></div>
	252	If the path to the configuration file itself is writeable
	253	by other users than <i>root</i> and the
	254	<i>effective user</i>
	255	these must be defined as trusted already
	256	at compile time.<br><br></dd>
	257	<dt><b><a name="Most frequently2">1.3. It does not log anything / Can't stop logging to console</a></b></dt>
	258	<dd>(1) There is a section in the manual dealing with
	259	logging and filtering.<br />
	260
	261	(2) To log to the console:
	262	<div class="block"><pre>
	263	$ samhain -p info ...
	264	</pre></div>
	265	or in the configuration file:
	266	<div class="block"><pre>
	267	[Log]
	268	PrintSeverity=info
	269	</pre></div>
	270
	271	To <i>stop</i> logging to the console:
	272	<div class="block"><pre>
	273	$ samhain -p none ...
	274	</pre></div>
	275	or in the configuration file:
	276	<div class="block"><pre>
	277	[Log]
	278	PrintSeverity=none
	279	</pre></div>
	280	Defining <tt>/dev/null</tt> as console device works as well, but
	281	is a bad idea, because samhain will open the device and write (i.e. it is
	282	a very inefficient method).<br><br></dd>
[538]	283	<dt><b><a name="Most frequently3">1.4. samhain exits with the message "Record with bad version number in file signature database"</a></b></dt>
	284	<dd>This typically happens when the initialisation of the database has been
	285	done repeatedly, i.e. by using '-t init' multiple times, without (re)moving
	286	the previous database first before an initialisation.<br><br></dd>
	287	<dt><b><a name="Most frequently4">1.5. Client cannot self-resolve, but nslookup works fine</a></b></dt>
[1]	288	<dd><ul>
	289	<li>Nslookup is a program to query Internet domain name servers.
	290	</li>
	291	<li>Applications (like samhain) are not supposed to query DNS servers
	292	directly. Rather, they are supposed to query the resolver library that:
	293	<ul>
	294	<li>is provided by the operating system,</li>
	295	<li>configured by the system administrator,</li>
	296	<li>may use several different method to determine host names, as
	297	configured in <tt>/etc/nsswitch.conf</tt>, and</li>
	298	<li>usually is configured to give precedence to
	299	the <tt>/etc/hosts</tt> file.</li>
	300	</ul>
	301	</li>
	302	<li>Therefore, whether nslookup gives correct answers may be completely
	303	irrelevant. For self-resolving the own hostname, the resolver
	304	library probably will use <tt>/etc/hosts</tt>, rather than
	305	querying a DNS server.
	306	</li>
	307	</ul>
	308	<p>
	309	Below you can find some examples of good and bad <tt>/etc/hosts</tt> files:
	310	</p>
	311	<div class="block"><pre>
	312	# CORRECT
	313	#
	314	127.0.0.1 localhost
	315	xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
	316	</pre></div>
	317
	318	<div class="block"><pre>
	319	# CORRECT
	320	#
	321	127.0.0.1 localhost.localdomain localhost
	322	xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
	323	</pre></div>
	324
	325	<div class="block"><pre>
	326	# BAD
	327	#
	328	127.0.0.1 myhost.mydomain.tld localhost
	329	xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
	330	</pre></div>
	331
	332	<div class="block"><pre>
	333	# BAD
	334	#
	335	127.0.0.1 localhost myhost
	336	xxx.xxx.xxx.xxx myhost.mydomain.tld myhost
	337	</pre></div><br><br></dd>
[538]	338	<dt><b><a name="Most frequently5">1.6. Server logs hostname instead of FQDN (or vice versa)</a></b></dt>
[462]	339	<dd>The default is to log the hostname only, if you want the FQDN
	340	then there is an option for the server configuration:
	341	<div class="block"><pre>
	342	[Misc]
	343	SetStripDomain = true / false
	344	</pre></div><br><br></dd>
[1]	345	</dl>
	346	<hr><h2>2. Build and install</h2>
	347	<dl>
[538]	348	<dt><b><a name="Build and install0">2.1. "make" loops infinitely !</a></b></dt>
[1]	349	<dd>This may happen (e.g. when building via NFS for multiple architectures)
	350	if the relative timestamps in the source directory are
	351	wrong (time not in sync on different machines) or some intermediate
	352	target is unusable (up-to-date, but built for a different OS). Use
	353	"touch * && make distclean" in the source directory
	354	to recover.<br><br></dd>
[538]	355	<dt><b><a name="Build and install1">2.2. Why does static compiling (<code>--enable-static</code>) on Solaris fail ?</a></b></dt>
[1]	356	<dd>Ingo Rogalsky has provided the following information: It isn't possible
	357	to link Samhain statically with Solaris. This
	358	is a Solaris issue (see Sun Infodoc ID12624) and not a samhain problem.<br><br></dd>
[538]	359	<dt><b><a name="Build and install2">2.3. Compilation fails with '/usr/bin/ld: cannot find -lnss_files'</a></b></dt>
[1]	360	<dd>For Linux, this is a known problem with --enable-static if you compile
	361	in MySQL support. The problem is that the
	362	<tt>mysql_config</tt> that comes as part of the MySQL
	363	distribution script incorrectly lists dependencies on
	364	the libnss_files and libnss_dns libraries which are only available as
	365	shared libraries, so the linker cannot find the static libraries.
	366
	367	You can check this by inspecting the output of
	368	<code>mysql_config --libs</code>. The version of
	369	<tt>mysql_config</tt> that comes with the RedHat mysql
	370	RPM (RedHat 9) does not have this bug; the one distributed by the MySQL
	371	people has. You can fix the problem by editing
	372	<tt>mysql_config</tt>: search for the
	373	<i>client_libs</i> variable, and remove all instances
	374	of <i>-lnss_files</i> and <i>-lnss_dns</i>.<br><br></dd>
[538]	375	<dt><b><a name="Build and install3">2.4. The executable is corrupted after installation</a></b></dt>
[1]	376	<dd>The executable will get stripped during the installation. On
	377	suitable systems (i386 Linux/FreeBSD currently), additionally
	378	the "sstrip"
	379	utility (copyright 1999 by Brian Raiter, under the GNU GPL)
	380	will be used to strip the executable even more, to prevent
	381	debugging with the GNU "gdb" debugger.
	382	The "strip" utility cannot handle the resulting
	383	executable, therefore trying to strip manually after installation
	384	will corrupt the executable.<br><br></dd>
[538]	385	<dt><b><a name="Build and install4">2.5. --enable-xml-log has no effect</a></b></dt>
[1]	386	<dd>If you have compiled for stealth, you won't see much, because if
	387	obfuscated, then both a 'normal' and an XML logfile look,
	388	well ... obfuscated. Use <code>samhain -jL /path/to/logfile</code>
	389	to view the logfile.<br><br></dd>
[538]	390	<dt><b><a name="Build and install5">2.6. ./install-sh: strip: not found (Solaris)</a></b></dt>
[1]	391	<dd>Install the SUNWbtool package.<br><br></dd>
[538]	392	<dt><b><a name="Build and install6">2.7. What is sh_tiger1.s?</a></b></dt>
[19]	393	<dd>This is a precompiled assembly file for the i386 architecture
	394	generated from sh_tiger1.c using gcc 3.4.0 with the following options,
	395	that were found to generate the fastest code:
	396	<pre>
	397	-O1 -fno-delayed-branch -fexpensive-optimizations -fstrength-reduce
	398	-fpeephole2 -fschedule-insns2 -fregmove -frename-registers -fweb
	399	-momit-leaf-frame-pointer -funroll-loops
	400	</pre>
	401	These options were determined using
	402	<a href="http://www.coyotegulch.com/products/acovea/">acovea</a> 5.1.1
	403	by Scott Robert Ladd. The file is provided as precompiled assembly
	404	because different versions of gcc can have very different performance,
	405	require different options to compile optimal code, and
	406	it would be impossible to maintain a library of optimal compile options
	407	for every version of gcc.<br><br></dd>
[538]	408	<dt><b><a name="Build and install7">2.8. Why does static compiling (<code>--enable-static</code>) on MaxOS X fail ?</a></b></dt>
[61]	409	<dd>Static linking is not supported on MacOS X, see
	410	<a href="http://developer.apple.com/qa/qa2001/qa1118.html">Technical Q&A QA1118</a>.
	411	This is a MacOS X issue and not a bug in samhain.<br><br></dd>
[538]	412	<dt><b><a name="Build and install8">2.9. Why does compiling with MySQL fail on Solaris ?</a></b></dt>
[101]	413	<dd>The reason is often the shell script 'mysql_config' that comes as part
	414	of MySQL. This script is intended to print appropriate compiler flags for
	415	compiling applications that use MySQL. Unfortunately, since Sun compiles
	416	MySQL with the Solaris compiler, this script outputs options for the Solaris
	417	compiler (i.e. unsuitable for gcc). To solve this problem, you need to move
	418	this script (i.e. 'mysql_config') out of your PATH before running
	419	<tt>./configure</tt> (unless of course you are using the Solaris compiler
	420	rather than gcc).<br><br></dd>
[1]	421	</dl>
	422	<hr><h2>3. File checking</h2>
	423	<dl>
	424	<dt><b><a name="File checking0">3.1. How can I exclude a (sub-)directory ?</a></b></dt>
	425	<dd><div class="block"><pre>
	426	[IgnoreAll]
	427	dir=-1/ignore/this/subdirectory
	428	</pre></div><br><br></dd>
	429	<dt><b><a name="File checking1">3.2. In messages about policy violations, what does the code after POLICY [XYZ]
	430	mean ?</a></b></dt>
	431	<dd>This code indicates which items are modified (e.g. C = checksum). You can
	432	find a description in section 5.4.9 in the user manual. It is there because
	433	then you can see in the message list of the Beltane web console what has been
	434	modified, without the need to look at the message in detail.<br><br></dd>
	435	<dt><b><a name="File checking2">3.3. Does samhain support prelink ?</a></b></dt>
	436	<dd>Yes. There is a special checking policy [Prelink]. Directories with
	437	prelinked executables / shared libraries (see /etc/prelink.conf) should be
	438	placed under this policy, rather than under the [ReadOnly] policy.<br><br></dd>
	439	<dt><b><a name="File checking3">3.4. I get error messages about 'subdirectory count != hardlinks'</a></b></dt>
	440	<dd>Some filesystems do not always follow the rule that the number
	441	of directory
	442	hardlinks equals the number of subdirectories. E.g. the root directory of
	443	reiserfs partitions generally seems to have two additional hardlinks.
	444	To account for such exceptions, you can either switch off the
	445	hardlink check globally, or specify exceptions:
	446	<div class="block"><pre>
	447	[Misc]
	448	# Switch off hardlink check
	449	#
	450	UseHardlinkCheck=no
	451	</pre></div>
	452	<div class="block"><pre>
	453	[Misc]
	454	# Specify exceptions for the hardlink check
	455	#
	456	HardlinkOffset=N:/path
	457	</pre></div>
	458	Here, N is the numerical offset (actual - expected hardlinks) for
	459	'/path'. For multiple exceptions, use
	460	this options multiple times (note that '/path N:/path2' would itself be a valid
	461	path, so using the option only once with multiple exceptions on the same line
	462	would be ambiguous).<br><br></dd>
	463	</dl>
	464	<hr><h2>4. Client/Server</h2>
	465	<dl>
	466	<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>
	467	<dd>Pat Smith has posted the following solution. On the client, create
	468	an iptable rule as follows (<i>note: you probably don't need this if you
	469	configure / compile in 127.0.0.1 as the server address</i>):
	470	<div class="block"><pre>
	471	iptables -t nat -A OUTPUT -p tcp -m tcp --dport 49777 -d <i>server-ip</i> -j REDIRECT
	472	</pre></div>
	473
	474	On the server, create an ssh tunnel for each client outside the firewall:
	475
	476	<div class="block"><pre>
	477	ssh -f -C -R 49777:localhost:49777 -N <i>client-ip</i>
	478	</pre></div>
	479
	480	It is necessary that each client has a distinct name, and that the server
	481	knows the name of the client. With the setup above, each client will appear
	482	as "localhost" to the server, thus the server
	483	needs to trust the client name
[101]	484	as reported by the client itself, and suppress all errors on resolving
[1]	485	this name to the apparent address. In the server configuration:
	486
	487	<div class="block"><pre>
	488	[Misc]
	489	SetClientFromAccept = false
	490	SeverityLookup = debug
	491	</pre></div>
	492
	493	Obviously, self-resolving must work on the client machine, otherwise
	494	you are in trouble (see next issue).<br><br></dd>
	495	<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>
	496	<dd>See 'Client cannot self-resolve' in the 'Most frequently' section<br><br></dd>
	497	<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>
	498	<dd>The client self-resolves to its ip address.
	499	See 'Client cannot self-resolve' in the 'Most frequently' section<br><br></dd>
	500	<dt><b><a name="Client/Server3">4.4. Cannot resolve client name host=XXX</a></b></dt>
	501	<dd><div class="block"><pre>
	502	The server must be able to determine the client name.
	503	This is because only authenticated connections from registered
	504	clients are allowed, and
	505	the server must be able to check the client hostname against the list of
	506	allowed hosts, and look up the password verifier for that
	507	host.
	508	</pre></div>
	509	There are two different ways to accomplish this. Unfortunately, judging
	510	from customer feedback as well from common sense, both do not work very well
	511	with a messed up local DNS (including /etc/hosts files) and/or
	512	überparanoid or misconfigured firewalls (in case of connections
	513	across one).
	514	<ul>
	515	<li>
	516	<p>
	517	<i>First method: Determine client name on client, and
	518	try to cross-check on server</i>
	519	<p>
	520	<p>
	521	This does not work for a number of people because (1) the
	522	<tt>/etc/hosts</tt> file on the client machine has errors
	523	(yes, there are plenty machines with a completely
	524	messed up <tt>/etc/hosts</tt> file), (2) the
	525	server cannot resolve the client address because the local DNS is
	526	f***ed up, or (3) the client machine has multiple network interfaces, and
	527	the interface used is not the one the client name resolves to.
	528	</p>
	529	<p>
	530	If the client uses the wrong interface on a multi-interface machine,
	531	there is a config file option
	532	<tt>SetBindAddress=</tt><i>IP address</i>
	533	that allows to choose the interface the client will use for
	534	outgoing connections.
	535	</p>
	536	<p>
	537	If you want to download the config file from the server, you
	538	should instead use the corresponding command line
	539	<tt>--bind-address=</tt><i>IP address</i>
	540	to select the interface.
	541	</p>
	542
	543	<p>
	544	If you encounter problems, you may (1) fix your
	545	<tt>/etc/hosts</tt> file(s), (2) fix your local DNS, or
	546	(3) switch to the second method.
	547	</p>
	548	<p>
	549	Errors in name resolving/cross-checking can be avoided by setting a
	550	very low severity (lower than the logging threshold), e.g.
	551	</p>
	552	<p>
	553	<tt>SeverityLookup=</tt><i>debug</i>
	554	</p>
	555	<p>
	556	in the <i>Misc</i> section of the server configuration,
	557	if you prefer running <i>unsafe</i> at any speed
	558	instead of fixing the problem (you have been warned). Doing so will
	559	allow an attacker to pose as the client.
	560	</p>
	561	</li>
	562	<li>
	563	<p><i>Second method: Use address of connecting entity as
	564	known to the communication layer</i></p>
	565	<p>
	566	This has been dropped as default
	567	long ago because it may not always be the
	568	address of the client machine.
	569	To enable this method, use
	570	</p>
	571	<p>
	572	<tt>SetClientFromAccept=</tt><i>true</i>
	573	</p>
	574	<p>
	575	in the <i>Misc</i> section of the server configuration
	576	file. If the address cannot be resolved, or reverse lookup of the
	577	resolved name fails, <i>no</i> error message will be issued,
	578	but the numerical address will be used.
	579	</p>
	580	</li>
	581	</ul><br><br></dd>
	582	<dt><b><a name="Client/Server4">4.5. Cannot resolve socket peer IP for client host=XXX peer=YYY</a></b></dt>
	583	<dd>See above<br><br></dd>
	584	<dt><b><a name="Client/Server5">4.6. Reverse lookup of socket peer failed host=XXX peer=YYY obj=ZZZ</a></b></dt>
	585	<dd>See above<br><br></dd>
	586	<dt><b><a name="Client/Server6">4.7. No socket peer alias matches client name host=XXX peer=YYY</a></b></dt>
	587	<dd>See above<br><br></dd>
	588	<dt><b><a name="Client/Server7">4.8. Session key negotiation failed</a></b></dt>
	589	<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
	590	<dt><b><a name="Client/Server8">4.9. Invalid connection attempt: Not in client list</a></b></dt>
	591	<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
	592	<dt><b><a name="Client/Server9">4.10. Invalid connection attempt: Session key mismatch</a></b></dt>
	593	<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
	594	<dt><b><a name="Client/Server10">4.11. How do I update the file signature database ?</a></b></dt>
	595	<dd>If you keep the file signature database on the server,
	596	the database is supposed to be updated on the server, using the
	597	<a href="http://www.la-samhna.de/beltane/">beltane</a>
	598	web-based console (currently in beta) and the
	599	log messages from the client.
	600	<p>
	601	Alternatively, you can <code>scp</code> the database
[101]	602	to the client, run <code>samhain -t update -l none --foreground</code>
	603	(you
[1]	604	need to avoid logging because otherwise you will get in conflict with
	605	the running samhain daemon), and then <code>scp</code> the
	606	database back to the server. Actually, with a properly set up
	607	"ssh", using RSA/DSA authentication
	608	and ssh-agent you could write a script to automate this.<br><br></dd>
	609	<dt><b><a name="Client/Server11">4.12. Time limit exceeded</a></b></dt>
	610	<dd>The respective client for that this message is generated has not
	611	sent anything for some interval of time (default 84600 sec = 1 day).
	612	The interval can be set as follows:
	613	<div class="block"><pre>
	614	[Misc]
	615	# unit is seconds
	616	SetClientTimeLimit=NNN
	617	</pre></div>
	618
	619	This feature has the purpose to detect if a client is dead. You
	620	might want to ensure that timestamps are sent to the server:
	621	<div class="block"><pre>
	622	[Log]
	623	ExportSeverity=mark
	624	</pre></div>
	625	If you don't want to use this feature, set the time limit to some
	626	very large value.<br><br></dd>
	627	<dt><b><a name="Client/Server12">4.13. Invalid connection attempt: Signature mismatch</a></b></dt>
	628	<dd>Clients sign their messages using a session key negotiated
	629	with the server. The message indicates that the server could
	630	not verify the signature. This may be caused by a running two
	631	instances of samhain on the same client machine, both of them
	632	accessing the server (and negotiating different session keys
	633	...). The system will recover automatically from the problem
	634	by forcing the failed client to negotiate a fresh session key.<br><br></dd>
	635	<dt><b><a name="Client/Server13">4.14. [Server] PANIC .. Address already in use   subroutine=bind</a></b></dt>
	636	<dd>The server cannot bind to its port because the port is already used.
	637	Maybe you have accidentially already an instance of the
	638	server running.<br><br></dd>
	639	</dl>
	640	<hr><h2>5. Email</h2>
	641	<dl>
	642	<dt><b><a name="Email0">5.1. Reverse lookup failed</a></b></dt>
	643	<dd>Fix your DNS (reverse lookup: numerical IP address to FQDN, to verify
	644	FQDN to numerical IP address).
	645	<div class="block"><pre>
	646	Whether "nslookup" works is not very informative, because
	647	"nslookup" does not use the resolver library of the operating
	648	system. Therefore,
	649	it is not exactly the
	650	best tool for debugging name resolving problems (see the book
	651	"DNS and bind").
	652	</pre></div><br><br></dd>
	653	<dt><b><a name="Email1">5.2. From daemon@example.com</a></b></dt>
	654	<dd>samhain fails to resolve the
	655	self-address of the host.
	656	See 'Client cannot self-resolve' in the 'Most frequently' section.<br><br></dd>
	657	<dt><b><a name="Email2">5.3. How do I define more than one email addresses ?</a></b></dt>
	658	<dd>Use <tt>SetMailAddress=...</tt> multiple times (upt to eight addresses
	659	are possible, with at most 63 characters per address):
	660	<div class="block"><pre>
	661	[Misc]
	662	SetMailAddress=aaa@foo.com
	663	SetMailAddress=bbb@foo.com
	664	</pre></div><br><br></dd>
	665	</dl>
	666	<hr><h2>6. Misc</h2>
	667	<dl>
	668	<dt><b><a name="Misc0">6.1. Error message: "Invalid line XYZ in configuration file"</a></b></dt>
	669	<dd>This message indicates that line XYZ in the configuration file contains
	670	an unrecognized directive. The primary reasons are:<br />
	671
	672	(a) The directive should be placed into a particular section of the
	673	configuration file, but the section header is not present (or you forgot
	674	to uncomment it).<br />
	675
	676	(b) Samhain is compiled without support for this directive.<br />
	677
	678	(c) You have a typo in the directive.<br /><br><br></dd>
	679	<dt><b><a name="Misc1">6.2. Why do I get a local logfile if I log to the server ?</a></b></dt>
	680	<dd>Because you can use all log facilities in parallel. You should
	681	switch off in the config file what you don't want/need:
	682	<div class="block"><pre>
	683	[Log]
	684	# local log file
	685	LogSeverity=none
	686	</pre></div><br><br></dd>
	687	<dt><b><a name="Misc2">6.3. Why is there no NIS support with a static samhain executable on Linux ?</a></b></dt>
	688	<dd>Some functions (including NIS) require
	689	libraries that are only available as shared libraries
	690	with modern GLIBC versions. While you can always compile a static
	691	executable, normally it would still open the shared library at runtime.
	692	As of version 1.8.11, samhain avoids this by providing replacement
	693	functions from uClibc. However, these do not include NIS support.<br><br></dd>
	694	<dt><b><a name="Misc3">6.4. Why do I get hundreds of messages about modified CTIME ?</a></b></dt>
	695	<dd>This happens because some
	696	backup applications reset the atime/mtime timestamps, which causes
	697	the ctime timestamp to be modified (rootkits avoid this by
	698	temporarily resetting the system clock to the original ctime ...).
	699	<p>
	700	To fix this problem, read the manual of your backup application, or
	701	redefine the ReadOnly policy to <i>not</i> check
	702	the ctime timestamp:
	703	<div class="block"><pre>
	704	[Misc]
	705	RedefReadOnly=-CTM
	706	</pre></div>
	707	<div class="warnblock"><pre>
	708	Order matters - you must <i>first</i> redefine
	709	ReadOnly <i>before</i> you use it
	710	</pre></div><br><br></dd>
	711	<dt><b><a name="Misc4">6.5. PANIC — File not accessible</a></b></dt>
	712	<dd>Most likely permission denied because of unsufficient privileges.<br><br></dd>
	713	<dt><b><a name="Misc5">6.6. How can I avoid error messages for invalid UIDs (no such user) ?</a></b></dt>
	714	<dd>Set SeverityNames to a low value
	715	<div class="block"><pre>
	716	[EventSeverity]
	717	SeverityNames=debug
	718	</pre></div><br><br></dd>
	719	<dt><b><a name="Misc6">6.7. [Redhat] The /etc/init.d/(samhain\|yule) init script hangs</a></b></dt>
	720	<dd>Redhat uses "initlog" (see
	721	<code>man initlog</code>) in initscripts. If it hangs, most probably
	722	samhain/yule runs in the foreground rather than as daemon. Set
	723	daemon mode in the configuration file:
	724	<div class="block"><pre>
	725	[Misc]
	726	Daemon=yes
	727	</pre></div><br><br></dd>
	728	<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>
	729	<dd>Either the program is not installed, or it is not in the PATH (the one
	730	used by the init script, which may be different from your PATH).<br><br></dd>
	731	<dt><b><a name="Misc8">6.9. Why am I not receiving the "BEGIN LOGKEY" message by email ?</a></b></dt>
	732	<dd>This message (which contains the key to verify the log file) is generated
	733	when logging to the log file starts. It has the severity "ALRT",
	734	thus you should make sure that you have set the logging threshold for
	735	email correctly to receive it.<br><br></dd>
	736	<dt><b><a name="Misc9">6.10. Why does console logging fail if I compile with
	737	<code>--enable-(micro-)stealth</code> ?</a></b></dt>
	738	<dd>The default logging options are more "stealthy". Set the
	739	threshold explicitely rather than relying on the default.<br><br></dd>
	740	<dt><b><a name="Misc10">6.11. I need a list for my schedule !</a></b></dt>
	741	<dd>You can have the same effect with a list of schedules. See the section
	742	"Timing file checks" in the manual.<br><br></dd>
	743	<dt><b><a name="Misc11">6.12. The hiding kernel module has no effect !</a></b></dt>
	744	<dd>Most probably you compiled using the wrong "System.map" file.<br><br></dd>
	745	<dt><b><a name="Misc12">6.13. What does the message "Large lstat/open overhead" mean ?</a></b></dt>
	746	<dd>Your system needs several seconds to proceed from an lstat() system call
	747	to an open() system call. This is a tremenduous overhead, and
	748	indicates that either your system has a really severe performance problem,
	749	or someone tries to slow down samhain.<br><br></dd>
	750	<dt><b><a name="Misc13">6.14. What does the message "Device not available path=/dev/random" mean ? I have /dev/random !</a></b></dt>
	751	<dd>/dev/random blocks unless there is some entropy it can deliver. Samhain
	752	will time out and fall back on /dev/urandom after some seconds to avoid
	753	hanging for a potentially long time. It will try /dev/random again next
	754	time it needs entropy.<br><br></dd>
	755	<dt><b><a name="Misc14">6.15. Logging to an external program fails; the program receives no data
	756	on stdin !</a></b></dt>
	757	<dd>Probably your program is not designed to <i>wait for input</i>, but exits
	758	if reading fails (because there is no data <i>yet</i>). You may want to
	759	let your program wait for the terminating "[EOF]" line.<br><br></dd>
	760	<dt><b><a name="Misc15">6.16. SIGILL on AIX</a></b></dt>
	761	<dd>For each scanned file, samhain needs to
	762	store some information in memory (e.g. to recognize changes that have
	763	already been reported, and avoid duplicate reports). On AIX, if you are
	764	checking a <i>really huge</i> number of files,
	765	memory usage may exceed the default limit of 256 MB, and the process may
	766	terminate with SIGILL.
	767	<p>
	768	The problem can be solved by linking with the flag
	769	<code>-bmaxdata:0x80000000</code>. This allows the application to
	770	access up to 8 segments (where each segment is 256MB).
	771	<p>
	772	If you are using gcc, you need to use instead
	773	the flag <code>-Wl,bmaxdata:0x80000000</code>, which tells
	774	gcc to pass on the
	775	<i>bmaxdata</i>
	776	flag to the AIX linker. You can use the LDFLAGS environment variable to
	777	pass linker flags to the configure script:
	778	<div class="block"><pre>
	779	export LDFLAGS="-Wl,bmaxdata:0x80000000"
	780	</pre></div><br><br></dd>
	781	</dl>
	782	<hr><h2>7. Database</h2>
	783	<dl>
	784	<dt><b><a name="Database0">7.1. Why are client messages corrupted / incompletely stored in the DB ?</a></b></dt>
	785	<dd>Because the messages are not in XML format, and therefore incorrectly
	786	parsed. The most frequent reasons are:
	787	<div class="block"><pre>
	788	1.) Your server is compiled with --enable-xml-log, but your client(s)
	789	is/are not.
	790
	791	2.) In your client or server configuration file, you are using
[19]	792	the option for a custom message header, but without paying attention
[1]	793	to preserving the XML format.
	794	</pre></div><br><br></dd>
	795	<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>
	796	<dd><div class="block"><pre>
	797	[Database]
	798	SetDBServerTstamp = true/false
	799	</pre></div>
	800
	801	This will enable/disable logging of the server timestamp for client
[553]	802	messages. The server timestamp will be written to a separate record,
[1]	803	with <i>log_ref</i> set to the value of
	804	<i>log_index</i> of the corresponding client message.<br><br></dd>
	805	<dt><b><a name="Database2">7.3. I don't want the client TIMESTAMP messages in the SQL database</a></b></dt>
	806	<dd><div class="block"><pre>
	807	Sending timestamps from the client allows the server to detect if
	808	a client is not running anymore (use SetClientTimeLimit=NNN in the
	809	[Misc] section of the server config file to set the number of seconds
	810	after which the server will issue an error message if no timestamp has
	811	been received).
	812	</pre></div>
	813
	814	However, you might not want to log these timestamps to the database
	815	(or other log facilities). To filter them, you can use two methods
	816	(examples are for the SQL database).
	817	The first
	818	one has the disadvantage that only messages of
	819	severity <i>err</i> or higher will be logged:
	820	<div class="block"><pre>
	821	[Misc]
	822	UseClientSeverity=yes
	823
	824	[Log]
	825	DatabaseSeverity=err
	826	</pre></div>
	827
	828	The second method is more specific — log everything not
	829	belonging to the STAMP class of messages:
	830	<div class="block"><pre>
	831	[Misc]
	832	UseClientClass=yes
	833
	834	[Log]
	835	DatabaseClass=PANIC RUN FIL TCP ERR ENET EINPUT
	836	</pre></div><br><br></dd>
	837	<dt><b><a name="Database3">7.4. What does the log_ref field mean ?</a></b></dt>
	838	<dd>NULL are client messages. Nonzero integer is a server timestamp
	839	for a client message (where log_ref indicates the log_index entry
	840	number of the corresponding client message). Zero indicates a message
	841	by the server itself (e.g. the server's start message).<br><br></dd>
[19]	842	<dt><b><a name="Database4">7.5. How can I check what is in the database ?</a></b></dt>
	843	<dd>Use a command line client to login to the database and query it:
	844	<div class="block"><pre>
	845	sh$ mysql -u <user_name> -p <database_name>
	846	Enter password: ****
	847	mysql> SELECT log_index,log_ref,log_host,log_sev,log_msg,path FROM <table_name> WHERE entry_status = 'NEW' ORDER BY log_index;
	848	....
	849	mysql> \q
	850	</pre></div><br><br></dd>
[1]	851	</dl>
	852	<hr>
	853
	854	<p>Copyright (c) 2004 Rainer Wichmann</p>
	855
	856	<p><i>This list of questions and answers was generated by
	857	<a href="http://www.makefaq.org/">makefaq</a>.</i>
	858
	859	</div>
	860	</body>
	861	</html>

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