Hello everyone.

First, I'm no linux expert. I know some basics of networking and windows servers mostly. And now I want to use a Linux distro (Centos 5.4) to build up a firewall for my servers on my hosting company.


What I want to / have to configure is:
- A linux router
- Which works on transparent routing mode (I guess its opposite to NAT mode)
- Which has Proxy-ARP feature.


My expected network plan is as follows:

Internet
|
|
Internet Gateway
ip = 10.0.0.1/24
|
|
Linux Firewall > Which I'm configuring
eth0 = 10.0.0.2/24, gw=10.0.0.1 , eth1 = 10.0.0.3/24
|
|
A server
ip= 10.0.0.5/24, gw=10.0.0.1


I guess I managed to enable Proxy-ARP and iptables, but I guess I couldn't configure routing.


My config is below:

cat /etc/sysctl.conf
net.ipv4.ip_forward = 1
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
net.ipv4.conf.eth1.proxy_arp = 1

netstat -nr
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
10.0.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 eth0
10.0.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1
0.0.0.0 10.0.0.1 0.0.0.0 UG 0 0 0 eth0

iptables -L -v
Chain INPUT (policy ACCEPT 7983 packets, 737K bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 31809 packets, 3221K bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 9930 packets, 1218K bytes)
pkts bytes target prot opt in out source destination


On the Linux Firewall, I can successfully ping 8.8.8.8 (or an external IP), 10.0.0.1, 10.0.0.2, 10.0.0.3 and 10.0.0.5.

But on the server (10.0.0.5), I can ping 10.0.0.2 only, I can't ping an external IP, 10.0.0.1 or 10.0.0.3.


Could you please help me to find out where the problem is.

As I said in the introduction, I'm not a network or linux guy

Thanks in advance.

>>Yasin