[CentOS] Routing problem

Marc Breslow marc at radiusIM.com
Tue Jul 18 16:16:25 UTC 2006


Thanks for the quick reply.

/proc/sys/net/ipv4/ip_forward contains 1.
Also, /etc/sysctl.conf was updated setting net.ipv4.ip_forward = 1. 
Also, /etc/sysconfig/network was updated adding FORWARD_IPV4=yes.

eth3 is on the firewall box and is connected to a switch shared by the 2nd
box (eth1).  eth1 on the firewall box connects to a different switch which
also has a connection to the router.

-----Original Message-----
From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On Behalf
Of Steve Huff
Sent: Tuesday, July 18, 2006 12:07 PM
To: CentOS mailing list
Subject: Re: [CentOS] Routing problem


On Jul 18, 2006, at 11:54 AM, Marc Breslow wrote:

> I want to provide internet connectivity to this 2nd machine routed  
> through the firewall.  Currently, I can reach two machines on the  
> 192.168.1.0/24 network (.5 and .3) but I can't reach the router (. 
> 1) or anything outside.
what does the file /proc/sys/net/ipv4/ip_forward contain (on the  
CentOS box that's connected to the router)?

if this file contains "0", your machine will not forward packets.

> Firewall routing tables:
>
> Kernel IP routing table
>
> Destination     Gateway         Genmask         Flags Metric Ref     
> Use Iface
>
> 10.0.0.0        0.0.0.0         255.255.255.254 U     0       
> 0        0 eth4
>
> 192.168.1.0     0.0.0.0         255.255.255.0   U     0       
> 0        0 eth1
>
> 192.168.202.0   0.0.0.0         255.255.255.0   U     0       
> 0        0 eth3
>
> 169.254.0.0     0.0.0.0         255.255.0.0     U     0       
> 0        0 eth4
>
> 0.0.0.0         192.168.1.1     0.0.0.0         UG    0       
> 0        0 eth1
>
>
>
> 192.168.202.10 routing table:
>
> Kernel IP routing table
>
> Destination     Gateway         Genmask         Flags Metric Ref     
> Use Iface
>
> 192.168.202.0   0.0.0.0         255.255.255.0   U     0       
> 0        0 eth1
>
> 10.1.16.0       0.0.0.0         255.255.240.0   U     0       
> 0        0 eth0
>
> 169.254.0.0     0.0.0.0         255.255.0.0     U     0       
> 0        0 eth0
>
> 0.0.0.0         192.168.202.1   0.0.0.0         UG    0       
> 0        0 eth1

are you sure that the machine 192.168.202.10 has an eth3 interface?   
i think you made a typo in your original message.  can you ping  
192.168.202.1 from the second machine?  what is the output of  
`traceroute 192.168.1.1`?

-steve

---
If this were played upon a stage now, I could condemn it as an  
improbable fiction. - Fabian, Twelfth Night, III,v



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