was using a WinME computer as my gateway with Norton firewall and thought it about time to swap it out with my Linux Computer. My Linux computer was on the network as a workstation with one NIC beforehand and working great. Here is what I did (btw running RedHat 8):

1. powered down computers
2. added 2nd NIC to the linux box
3. booted the linux box up
4. (getting odd @ address at prompt) after some research found I needed to remain my computer name in the network file. Contents of /etc/sysconfig/network now:
NETWORKING=yes
HOSTNAME=linux
FORWARD_IPV4=true

5. Could now connect to the internet from Linux.
6. Could not connect to linux from my windows computer.
7. Stopped IPTABLES (custom script, probably has errors).
8. Had a few more problems and realized named wasn't running.
9. Started service named
10. Now can see Linux fine from the windows computer, but cannot see the internet from the windows computer. Names are translating though (IE finds the IP, just can't connect).

This is where I am stuck. Looks like it may be due to forwarding or routing.

ifconfig output:
eth0 Link encap:Ethernet HWaddr 00:50:DA:07:33:C9
inet addr:12.252.107.87 Bcast:255.255.255.255 Mask:255.255.254.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:26778 errors:0 dropped:0 overruns:0 frame:0
TX packets:3543 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:3971760 (3.7 Mb) TX bytes:559263 (546.1 Kb)
Interrupt:11 Base address:0xa800

eth1 Link encap:Ethernet HWaddr 00:A0:CC:3B:EA:9F
inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:8603 errors:1 dropped:0 overruns:0 frame:0
TX packets:7652 errors:12 dropped:0 overruns:0 carrier:0
collisions:162 txqueuelen:100
RX bytes:1030854 (1006.6 Kb) TX bytes:1380291 (1.3 Mb)
Interrupt:9 Base address:0xd000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:538 errors:0 dropped:0 overruns:0 frame:0
TX packets:538 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:70213 (68.5 Kb) TX bytes:70213 (68.5 Kb)


Route output:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.0.0 * 255.255.255.0 U 0 0 0 eth1
12.252.106.0 * 255.255.254.0 U 0 0 0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default 12-252-106-1.cl 0.0.0.0 UG 0 0 0 eth0

BTW, my IPTables script changes the kernel parms. Piece of the IPTables script (got this script from one of the tutorials on the IPTables web site):


/bin/echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_all
/bin/echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
/bin/echo "0" > /proc/sys/net/ipv4/conf/all/accept_source_route
for interface in /proc/sys/net/ipv4/conf/*/accept_redirects; do
/bin/echo "0" > ${interface}
done
/bin/echo "1" > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses
for interface in /proc/sys/net/ipv4/conf/*/rp_filter; do
/bin/echo "1" > ${interface}
done
/bin/echo "0" > /proc/sys/net/ipv4/conf/all/log_martians
/bin/echo "1" > /proc/sys/net/ipv4/ip_forward


I have IPTables accepting all at the moment until I get this working so that shouldn't be the issue.

Thank you.

try the following lines:
#****** allow forwarding **********
iptables -A FORWARD -m state --state NEW -i eth1 -j ACCEPT
iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT

if your eth0 ip is dynamic one: do masquerading
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

or in case of static ip:
iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to-source=12.252.107.87

should do.
and don't worry about lines like "/bin/echo "1" > ....." - they make some firewall settings
important is
/bin/echo "1" > /proc/sys/net/ipv4/ip_forward
which has to be to allow forwarding

Confirm the netmask and gateway numbers you need to use for eth0.
snip
eth0 Link encap:Ethernet HWaddr 00:50:DA:07:33:C9
inet addr:12.252.107.87 Bcast:255.255.255.255 Mask:255.255.254.0

That one looks very suspicious...

Got it working. Needed to add the forwarding lines to iptables to get it to work. When I had iptables "off" to test, I also had the forwarding rules off.