From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Taylor, Grant" <gtaylor@riverviewtech.net>
Subject: Re: routing within same nic card
Date: Tue, 31 May 2005 00:49:26 -0500
Message-ID: <429BFAE6.90200@riverviewtech.net>
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> I have 1 NIC card with 2 ip address:
> IP1 = 192.168.3.1/255.255.255.192
> Network 1 = 192.168.3.0/255.255.255.192
> 
> IP2 = 192.168.4.1/255.255.255.248
> Network 2 = 192.168.4.0/255.255.255.248
> 
> My question, how can workstations from network 1 reaches the 
> workstations in network 2 and vice versa  using IPtables?

This really is not an IPTables issue as this is more a routing issue than it is a packet filtering issue.  All you need to do to enable the ""routing would be to enable IP forwarding via one of these two methods:

sysctl -w net.ipv4.ip_forward=1

or

echo "1" > /proc/sys/net/ipv4/ip_forward

The only thing that IPTables might be interfering with this on would be if you have your default FORWARD policy to DROP.  In that case you would need to do something like the following:

iptables -t filter -A FORWARD -i eth0 -o eth0 -j ACCEPT

Or if you want to be more specific and specify what subnets can forward you would need the following rules:

iptables -t filter -A FORWARD -i eth0 -o eth0 -s 192.168.3.0/24 -d 192.168.4.0/24 -j ACCEPT
iptables -t filter -A FORWARD -i eth0 -o eth0 -s 192.168.4.0/24 -d 192.168.3.0/24 -j ACCEPT



Grant. . . .