problem with two lan cards

prasadlinuxguy · 05-16-2006, 12:16 AM

i use RedHat EL4 on my system.i have two lancards on my system one to connect to internet and the other to another system in my home.both lan cards are of the same kind.

first i thought that the internet connection was not working but when i switched the line to the other card the connection resumed.but this time pinging between the systems did'nt work.after sometime the internet stopped,i switched the line again to the other card and it resumed.but pinging the lines never seems to work.

the subnet mask given by isp was 255.255.255.0 and the ipaddress was 192.168.1.2 . so i configured card on my system as 192.168.1.24 and the card on other system as 192.6.1.34.the connection is dsl with speed 64kbps and the vendor says that he does'nt use any ppp0e or protocals of
the like.

please help me solve the problem.

gundam00 · 05-16-2006, 02:13 AM

First of all you should verify if your Linux permits routing over the interfaces:
the file /proc/sys/net/ipv4/ip_forward should contains the value 1.

Just to be sure try with:

Code:

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

Then you have to make NAT between your home net net and the isp net, if you have set up a firewall you have to enable forwarding from your network and then you have to enable NAT:

Code:

iptables -P FORWARD ACCEPT
iptables -F FORWARD
iptables -I POSTROUTING -t nat -s <YOUR HOME NET> -j MASQUERADING

Assuming that your network configurations are ok, if ip_forward and NAT are set up you should be able to ping over your linux box.

wraithe · 05-16-2006, 02:23 AM

hey can i ask a dumb question here?
well i will any way...
what is the irq of the two cards...
i have seen this before and most times its the first thing to check...
when you use two cards the same they both try to use the same irq and if you boot with one card first and run the install then add the other it can cure it ....
let me know if that dont work, but i'm sure that is the best place to start with...
dont feel silly as i have seen some so called great eggspurts not check that one ok....