2002-08-13 22:45:21 +02:00
|
|
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
|
|
|
|
|
<html>
|
|
|
|
|
|
<head>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<meta http-equiv="Content-Type"
|
|
|
|
|
|
content="text/html; charset=windows-1252">
|
2002-08-13 22:45:21 +02:00
|
|
|
|
<title>Shorewall Troubleshooting</title>
|
|
|
|
|
|
<meta name="GENERATOR" content="Microsoft FrontPage 5.0">
|
|
|
|
|
|
<meta name="ProgId" content="FrontPage.Editor.Document">
|
2002-11-09 19:06:34 +01:00
|
|
|
|
</head>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<body>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<h1 align="center" style="background-color: rgb(255, 255, 255);">Shorewall
|
|
|
|
|
|
Troubleshooting <img src="images/obrasinf.gif"
|
|
|
|
|
|
alt="Beating head on table" style="width: 90px; height: 90px;"
|
|
|
|
|
|
align="middle" title=""></h1>
|
2003-10-07 00:38:40 +02:00
|
|
|
|
<h3 style="text-align: center;"><span style="font-style: italic;">"If
|
|
|
|
|
|
you think you can you can; if you think you can't you're right.<br>
|
|
|
|
|
|
If you don't believe that you can, why should someone else?" -- Gunnar
|
|
|
|
|
|
Tapper<br>
|
|
|
|
|
|
</span></h3>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<h3 align="left">Check the Errata</h3>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<p align="left">Check the <a href="errata.htm">Shorewall Errata</a> to
|
|
|
|
|
|
be sure that there isn't an update that you are missing for your
|
|
|
|
|
|
version of the firewall.</p>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<h3 align="left">Check the FAQs</h3>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<p align="left">Check the <a href="FAQ.htm">FAQs</a> for solutions to
|
|
|
|
|
|
common problems.</p>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<h3 align="left">If the firewall fails to start</h3>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
If you receive an error message when starting or restarting the
|
|
|
|
|
|
firewall and you can't determine the cause, then do the following:
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<ul>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<li>Make a note of the error message that you see.<br>
|
|
|
|
|
|
</li>
|
|
|
|
|
|
<li>shorewall debug start 2> /tmp/trace</li>
|
|
|
|
|
|
<li>Look at the /tmp/trace file and see if that helps you determine
|
|
|
|
|
|
what the problem is. Be sure you find the place in the log where the
|
|
|
|
|
|
error message you saw is generated -- If you are using Shorewall 1.4.0
|
|
|
|
|
|
or later, you should find the message near the end of the log.</li>
|
|
|
|
|
|
<li>If you still can't determine what's wrong then see the <a
|
|
|
|
|
|
href="support.htm">support page</a>.</li>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
</ul>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
Here's an example. During startup, a user sees the following:<br>
|
|
|
|
|
|
<blockquote>
|
2002-12-28 16:38:03 +01:00
|
|
|
|
<pre>Adding Common Rules<br>iptables: No chain/target/match by that name<br>Terminated<br></pre>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
</blockquote>
|
|
|
|
|
|
A search through the trace for "No chain/target/match by that name"
|
|
|
|
|
|
turned up the following:
|
|
|
|
|
|
<blockquote>
|
2002-12-28 16:38:03 +01:00
|
|
|
|
<pre>+ echo 'Adding Common Rules'<br>+ add_common_rules<br>+ run_iptables -A reject -p tcp -j REJECT --reject-with tcp-reset<br>++ echo -A reject -p tcp -j REJECT --reject-with tcp-reset<br>++ sed 's/!/! /g'<br>+ iptables -A reject -p tcp -j REJECT --reject-with tcp-reset<br>iptables: No chain/target/match by that name<br></pre>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
</blockquote>
|
|
|
|
|
|
The command that failed was: "iptables -A reject -p tcp -j REJECT
|
|
|
|
|
|
--reject-with tcp-reset". In this case, the user had compiled his own
|
|
|
|
|
|
kernel and had
|
|
|
|
|
|
forgotten to include REJECT target support (see <a href="kernel.htm">kernel.htm</a>)
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<h3>Your network environment</h3>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<p>Many times when people have problems with Shorewall, the problem is
|
|
|
|
|
|
actually an ill-conceived network setup. Here are several popular
|
|
|
|
|
|
snafus: </p>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<ul>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<li>Port Forwarding where client and server are in the same subnet.
|
|
|
|
|
|
See <a href="FAQ.htm">FAQ 2.</a></li>
|
|
|
|
|
|
<li>Changing the IP address of a local system to be in the external
|
|
|
|
|
|
subnet, thinking that Shorewall will suddenly believe
|
|
|
|
|
|
that the system is in the 'net' zone.</li>
|
|
|
|
|
|
<li>Multiple interfaces connected to the same HUB or Switch. Given
|
|
|
|
|
|
the way that the Linux kernel respond to ARP "who-has" requests, this
|
|
|
|
|
|
type of setup does NOT work the way that you expect it to. If you
|
|
|
|
|
|
are running Shorewall version 1.4.7 or later, you can test using this
|
|
|
|
|
|
kind of configuration if you specify
|
|
|
|
|
|
the <span style="font-weight: bold;">arp_filter</span>
|
|
|
|
|
|
option in /etc/shorewall/interfaces for all interfaces connected to the
|
|
|
|
|
|
common hub/switch. Using such a setup with a production firewall is
|
|
|
|
|
|
strongly recommended against.</li>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
</ul>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<h3 align="left">If you are having connection problems:</h3>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<p align="left">If the appropriate policy for the connection that you
|
|
|
|
|
|
are trying to make is ACCEPT, please DO NOT ADD ADDITIONAL ACCEPT RULES
|
|
|
|
|
|
TRYING TO MAKE IT WORK. Such additional rules will NEVER make it work,
|
|
|
|
|
|
they add clutter to your rule set and they represent a big security
|
|
|
|
|
|
hole
|
|
|
|
|
|
in the event that you forget to remove them later.</p>
|
|
|
|
|
|
<p align="left">I also recommend against setting all of your policies
|
|
|
|
|
|
to ACCEPT in an effort to make something work. That robs you of one of
|
|
|
|
|
|
your best diagnostic tools - the "Shorewall" messages that Netfilter
|
|
|
|
|
|
will generate when you try to connect in a way that isn't permitted by
|
|
|
|
|
|
your rule set.</p>
|
|
|
|
|
|
<p align="left">Check your log ("/sbin/shorewall show log"). If you
|
|
|
|
|
|
don't see Shorewall messages, then your problem is probably NOT a
|
|
|
|
|
|
Shorewall problem. If you DO see packet messages, it may be an
|
|
|
|
|
|
indication that
|
|
|
|
|
|
you are missing one or more rules -- see <a href="FAQ.htm#faq17">FAQ 17</a>.</p>
|
|
|
|
|
|
<p align="left">While you are troubleshooting, it is a good idea to
|
|
|
|
|
|
clear two variables in /etc/shorewall/shorewall.conf:</p>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<p align="left">LOGRATE=""<br>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
LOGBURST=""</p>
|
|
|
|
|
|
<p align="left">This way, you will see all of the log messages being
|
|
|
|
|
|
generated (be sure to restart shorewall after clearing these variables).</p>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<p align="left">Example:</p>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<font face="Century Gothic, Arial, Helvetica">
|
|
|
|
|
|
<p align="left"><font face="Courier">Jun 27 15:37:56 gateway kernel:
|
|
|
|
|
|
Shorewall:all2all:REJECT:IN=eth2 OUT=eth1 SRC=192.168.2.2
|
|
|
|
|
|
DST=192.168.1.3 LEN=67 TOS=0x00 PREC=0x00 TTL=63 ID=5805 DF PROTO=UDP
|
|
|
|
|
|
SPT=1803 DPT=53 LEN=47</font></p>
|
|
|
|
|
|
</font>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<p align="left">Let's look at the important parts of this message:</p>
|
|
|
|
|
|
<ul>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<li>all2all:REJECT - This packet was REJECTed out of the
|
|
|
|
|
|
all2all chain -- the packet was rejected under the "all"->"all"
|
|
|
|
|
|
REJECT policy (see <a href="FAQ.htm#faq17">FAQ 17).</a></li>
|
|
|
|
|
|
<li>IN=eth2 - the packet entered the firewall via eth2</li>
|
|
|
|
|
|
<li>OUT=eth1 - if accepted, the packet would be sent on eth1</li>
|
|
|
|
|
|
<li>SRC=192.168.2.2 - the packet was sent by 192.168.2.2</li>
|
|
|
|
|
|
<li>DST=192.168.1.3 - the packet is destined for 192.168.1.3</li>
|
|
|
|
|
|
<li>PROTO=UDP - UDP Protocol</li>
|
|
|
|
|
|
<li>DPT=53 - DNS</li>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
</ul>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<p align="left">In this case, 192.168.2.2 was in the "dmz" zone and
|
|
|
|
|
|
192.168.1.3 is in the "loc" zone. I was missing the rule:</p>
|
|
|
|
|
|
<p align="left">ACCEPT dmz
|
|
|
|
|
|
loc udp 53<br>
|
|
|
|
|
|
</p>
|
|
|
|
|
|
<p align="left">See <a href="FAQ.htm#faq17">FAQ 17</a> for additional
|
|
|
|
|
|
information about how to interpret the chain name appearing in a
|
|
|
|
|
|
Shorewall log message.<br>
|
|
|
|
|
|
</p>
|
2003-01-14 18:18:42 +01:00
|
|
|
|
<h3 align="left">'Ping' Problems?</h3>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
Either can't ping when you think you should be able to or are able to
|
|
|
|
|
|
ping when you think that you shouldn't be allowed? Shorewall's 'Ping'
|
|
|
|
|
|
Management<a href="ping.html"> is described here</a>.<br>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<h3 align="left">Other Gotchas</h3>
|
|
|
|
|
|
<ul>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<li>Seeing rejected/dropped packets logged out of the INPUT or
|
|
|
|
|
|
FORWARD chains? This means that:
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<ol>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<li>your zone definitions are screwed up and the host that is
|
|
|
|
|
|
sending the packets or the destination host isn't in any zone (using an
|
|
|
|
|
|
<a href="Documentation.htm#Hosts">/etc/shorewall/hosts</a> file
|
|
|
|
|
|
are you?); or</li>
|
|
|
|
|
|
<li>the source and destination hosts are both connected to the
|
2003-12-03 00:51:46 +01:00
|
|
|
|
same interface and you haven't specified the 'routeback' option on that
|
|
|
|
|
|
interface.</li>
|
2002-09-16 19:13:10 +02:00
|
|
|
|
</ol>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
</li>
|
|
|
|
|
|
<li>Remember that Shorewall doesn't automatically allow ICMP type 8
|
|
|
|
|
|
("ping") requests to be sent between zones. If you want pings to be
|
|
|
|
|
|
allowed between zones, you need a rule of the form:<br>
|
|
|
|
|
|
<br>
|
|
|
|
|
|
ACCEPT <source
|
|
|
|
|
|
zone> <destination zone>
|
|
|
|
|
|
icmp echo-request<br>
|
|
|
|
|
|
<br>
|
|
|
|
|
|
The ramifications of this can be subtle. For example, if you have the
|
|
|
|
|
|
following in /etc/shorewall/nat:<br>
|
|
|
|
|
|
<br>
|
|
|
|
|
|
10.1.1.2 eth0
|
|
|
|
|
|
130.252.100.18<br>
|
|
|
|
|
|
<br>
|
|
|
|
|
|
and you ping 130.252.100.18, unless you have allowed icmp type 8
|
|
|
|
|
|
between the zone containing the system you are pinging from and the
|
|
|
|
|
|
zone containing 10.1.1.2, the ping requests will be dropped. </li>
|
|
|
|
|
|
<li>If you specify "routefilter" for an interface, that interface
|
|
|
|
|
|
must be up prior to starting the firewall.</li>
|
|
|
|
|
|
<li>Is your routing correct? For example, internal systems usually
|
|
|
|
|
|
need to be configured with their default gateway set to
|
|
|
|
|
|
the IP address of their nearest firewall interface. One often
|
|
|
|
|
|
overlooked aspect of routing is that in order for two hosts to
|
|
|
|
|
|
communicate,
|
|
|
|
|
|
the routing between them must be set up <u>in both directions.</u>
|
|
|
|
|
|
So when setting up routing between <b>A</b> and<b> B</b>, be sure
|
|
|
|
|
|
to verify that the route from <b>B</b> back to <b>A</b> is defined.</li>
|
|
|
|
|
|
<li>Some versions of LRP (EigerStein2Beta for example) have a shell
|
|
|
|
|
|
with broken variable expansion. <a
|
|
|
|
|
|
href="ftp://ftp.shorewall.net/pub/shorewall/ash.gz"> You can get a
|
|
|
|
|
|
corrected shell from the Shorewall Errata download site.</a> </li>
|
|
|
|
|
|
<li>Do you have your kernel properly configured? <a href="kernel.htm">Click
|
|
|
|
|
|
here to see my kernel configuration.</a> </li>
|
|
|
|
|
|
<li>Shorewall requires the "ip" program. That program is generally
|
|
|
|
|
|
included in the "iproute" package which should be included with your
|
|
|
|
|
|
distribution (though many distributions don't install iproute by
|
|
|
|
|
|
default). You may also download the latest source tarball from <a
|
|
|
|
|
|
href="ftp://ftp.inr.ac.ru/ip-routing" target="_blank">
|
|
|
|
|
|
ftp://ftp.inr.ac.ru/ip-routing</a> .</li>
|
|
|
|
|
|
<li>Problems with NAT? Be sure that you let
|
|
|
|
|
|
Shorewall add all external addresses to be use with NAT unless you
|
|
|
|
|
|
have set <a href="Documentation.htm#Aliases"> ADD_IP_ALIASES</a> =No
|
2003-07-16 20:59:33 +02:00
|
|
|
|
in /etc/shorewall/shorewall.conf.</li>
|
2002-11-24 21:08:19 +01:00
|
|
|
|
</ul>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<h3>Still Having Problems?</h3>
|
2003-01-14 18:18:42 +01:00
|
|
|
|
<p>See the<a href="support.htm"> support page.<br>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
</a></p>
|
|
|
|
|
|
<font face="Century Gothic, Arial, Helvetica">
|
2002-11-09 19:06:34 +01:00
|
|
|
|
<blockquote> </blockquote>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
</font>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<p><font size="2">Last updated 11/1/2003 - Tom Eastep</font> </p>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
<p><font face="Trebuchet MS"><a href="copyright.htm"><font size="2">Copyright</font>
|
2003-08-09 19:14:58 +02:00
|
|
|
|
<EFBFBD> <font size="2">2001, 2002 Thomas M. Eastep.</font></a></font><br>
|
|
|
|
|
|
</p>
|
|
|
|
|
|
<br>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
</body>
|
2002-11-09 19:06:34 +01:00
|
|
|
|
</html>
|
