Dual Network Card in RH7.3
 

What i have now:

I have 1 server with 2 network cards:

NIC1
- Static IP (219.93.225.x)
- connects to a switch that gives me DSL connection

NIC2
- Internal IP (192.168.100.x)
- connects to a switch to my LAN


What i'm trying to achieve:

1. Let my LAN users access the server internally
2. Use the server to host my website


I would like to map watever request from NIC2 to NIC1 so that watever request is processed transparently to the users.
Since this is gona expose my LAN, i figured that i should have a firewall for security.
Is there any software on RH7.3 that allows me to do this? If yes, how?
Thanks in advance

Welcome to LQ.

You can do all of what you want with iptables. There is a good tutorial here:
http://www.yolinux.com/TUTORIALS/Lin...rkGateway.html

As well as lots more info on this site - just post if you have problems.

Hi,

Thanks for the reply.
I've read the link that you've sent me and tried it.

I'm looking at the section Example 2: Linux connected via DSL, Cable, T1

I get an error at the final "route" command:

[root@demo empDomain]# ipchains -F forward
[root@demo empDomain]# ipchains -P forward DENY
[root@demo empDomain]# ipchains -A forward -s 192.168.100.0/24 -j MASQ
Warning: you must enable IP forwarding for packets to be forwarded at all:
Use `echo 1 > /proc/sys/net/ipv4/ip_forward'
[root@demo empDomain]# echo 1 > /proc/sys/net/ipv4/ip_forward
[root@demo empDomain]# route add -net 192.168.100.0 netmask 255.255.255.0 gw 219.93.225.xx dev eth1
SIOCADDRT: Network is unreachable



If it makes any difference here are my NIC's information:

eth0:
IP: 219.93.225.x
Subnet: 255.255.255.248
Gateway: 219.93.225.xx

eth1:
IP: 192.168.100.28
Subnet: 255.255.255.0

I think if you search the web, there is a HOWTO on masquerading. That is what you are looking for- a firewall that masquerades. I found one that has some configurable options in it, but there is no gui interface. Just a text file. I am also running 7.3, and my server hosts a website, as well as ssh logins from the internet. The internal network has free-flow.

Scott

PS I found that when using such a firewall, you do NOT start ipchains in the normal startup process.

You may need to chek your routing table does not have these entries already and that it accomodates the networks involved:
route -n

Route table....doesn't seem to be any problems or maybe i just dont know what i'm doing :)
any ideas...anybody??


[root@demo bin]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
219.93.225.xxx 0.0.0.0 255.255.255.xxx U 0 0 0 eth0
192.168.100.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 219.93.225.xx3 0.0.0.0 UG 0 0 0 eth0

man, you really should be using iptables and not ipchains

also for that forwarding problem:

in redhat edit the following file:


/etc/sysctl.conf

there is a line (probably the 1st line) that say:

net.ipv4.ip_forward=0

change it to

net.ipv4.ip_forward=1 to turn on ipforwarding

also, you'll need to run the following command (just this once so taht you dont have to boot to get forwarding to work)

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

I've tried chaging from ipchains to iptables following the steps listed on this website:

http://www.yolinux.com/TUTORIALS/Lin...rkGateway.html


I'm still stuck at the route command:

[root@demo empDomain]# route add -net 192.168.100.0 netmask 255.255.255.0 gw 219.93.225.xx dev eth1
SIOCADDRT: Network is unreachable


Now my external IP isn't working anymore. Cant connect to it at all.
I'm lost...

That shoudln't affect your network if the add failed. Can you post:
route -n

Here goes....
I think i probably screwed something up somewhere....

# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.100.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
219.93.225.0 219.93.225.xx3 255.255.255.0 UG 0 0 0 eth0
219.93.225.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 219.93.225.xx3 0.0.0.0 UG 0 0 0 eth0

i've managed to reconfigure my route to the original one (refer post #6 for my earlier route -n)....
but my external IP is still not working
i think i must've screwed up something in the midst of configuring iptables
any ideas? or where should i look to rectify this?

You say your external IP isn;t working - does it work from the linux box itself or is it just a problem for the clients?

yes...it does work from the box itself as there's a reply when i try to ping it
like you said...its just a problem with the clients

Then the forwarding doesn't seem to be working. Can you post:
iptables -L

$iptables -L

Chain INPUT (policy ACCEPT)
target prot opt source destination
LOG all -- anywhere anywhere LOG level warning prefix `INPUT_DROP: '

Chain FORWARD (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere

Chain OUTPUT (policy ACCEPT)
target prot opt source destination
LOG all -- anywhere anywhere LOG level warning prefix `OUTPUT_DROP: '