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06/26/2006 at 12:57AM PDT, ID: 21898879
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7.6

Unable to traceroute behind and from server running Linux Firewall

Asked by psd_steve in Linux Network Security

Tags: traceroute

Cheers,

 Ok here is my setup. I am running a CentOS 4 server with 3 Nics:

eth0      Link encap:Ethernet  HWaddr 00:13:20:EC:9A:21
          inet addr:192.168.1.62  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::213:20ff:feec:9a21/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:60413 errors:0 dropped:0 overruns:0 frame:0
          TX packets:94747 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:26805419 (25.5 MiB)  TX bytes:9087449 (8.6 MiB)

eth1      Link encap:Ethernet  HWaddr 00:08:54:D8:39:D0
          inet addr:192.168.200.1  Bcast:192.168.200.255  Mask:255.255.255.0
          inet6 addr: fe80::208:54ff:fed8:39d0/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:136158 errors:0 dropped:0 overruns:0 frame:0
          TX packets:129352 errors:0 dropped:0 overruns:1 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:12276407 (11.7 MiB)  TX bytes:131825811 (125.7 MiB)
          Interrupt:193 Base address:0x1100

eth2      Link encap:Ethernet  HWaddr 00:08:54:DE:22:10
          inet addr:192.168.44.1  Bcast:192.168.44.255  Mask:255.255.255.0
          inet6 addr: fe80::208:54ff:fede:2210/64 Scope:Link
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
          Interrupt:201 Base address:0x1000

eth0 is hooked to a wireless and is our incoming Internet connection. I run 2 subnets off the box the .200 and .44 The box is running DHCP for both nets. I have no problems pinging any address from behind the firewall, When I  run traceroute from the server:
[user@psd ~]# traceroute www.experts-exchange.com
traceroute to experts-exchange.com (64.156.132.140), 30 hops max, 38 byte packets
 1  * * *
 2  * * *
 3  * * *
 when I run traceroute from a machine behind the server:

C:\Documents and Settings\user\tracert www.experts-exchange.com

traceing route  to experts-exchange.com (64.156.132.140)
over a maximum of  30 hops:
 1  <1 ms   <1 ms   < 1ms
 2  * * *
 3  * * *
 4  * * *
 |
 |
13 707 ms    930 ms   741 mx    www-level13.experts-exchange.com  [64.156.132.140]

Trace complete.

I have the firewall filtering connections by MAC address on eth2

here is my iptables from /etc/sysconfig/

 Generated by iptables-save v1.2.11 on Fri Jun  2 10:56:49 2006
*nat
:PREROUTING DROP [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A PREROUTING -i eth0 -j ACCEPT
-A PREROUTING -m mac -i eth2 --mac-source 00:11:09:21:B0:2F -j ACCEPT
-A PREROUTING -m mac -i eth2 --mac-source 00:11:F5:17:01:10 -j ACCEPT
--------------------**  8<       cut out a lot of other MAC accept lines for Brevity       >8  **------------------------------------------------A POSTROUTING -o eth0 -j MASQUERADE
-A PREROUTING -i eth1 -j ACCEPT
-A POSTROUTING -o eth1 -j ACCEPT
COMMIT
# Completed on Fri Jun  2 10:56:49 2006
# Generated by iptables-save v1.2.11 on Fri Jun  2 10:56:49 2006
*mangle
:PREROUTING ACCEPT [78:8830]
:INPUT ACCEPT [56:7598]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [45:6368]
:POSTROUTING ACCEPT [45:6368]
COMMIT
# Completed on Fri Jun  2 10:56:49 2006
# Generated by iptables-save v1.2.11 on Fri Jun  2 10:56:49 2006
*filter
:INPUT ACCEPT [56:7598]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [45:6368]
COMMIT
# Completed on Fri Jun  2 10:56:49 2006


I am using Webmin 1.250 to set things up. I am by no means a guru, learning as I go reading as much as I can. I was unable to get things to work by setting eth0 to a static IP so I settled for using DHCP on eth0. I'll worry about that one after I fix this one. Thanks in advance.

Steve


[+][-]06/26/06 05:48 AM, ID: 16983513

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[+][-]06/26/06 12:43 PM, ID: 16987123

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[+][-]06/26/06 01:03 PM, ID: 16987266

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[+][-]06/26/06 02:01 PM, ID: 16987785

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[+][-]06/26/06 02:10 PM, ID: 16987878

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[+][-]06/26/06 02:31 PM, ID: 16988056

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[+][-]06/26/06 02:52 PM, ID: 16988204

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[+][-]07/11/06 01:55 PM, ID: 17085438

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About this solution

Zone: Linux Network Security
Tags: traceroute
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Solution Provided By: noci
Participating Experts: 2
Solution Grade: A
 
 
 
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