I am a telecommunications engineer who has run into a network trouble when using a communications system simulator on CentOS.
This is how my simulator and network are setup -
- The simulator runs on CentOS 5.5 on VMware.
- I've setup 2 ethernet interfaces ->
eth0 (public) with IP address 148.147.134.XXX and gateway 126.96.36.199. This is connected to my corporate LAN.
eth 1 (private) with IP address 10.30.30.2 and gateway 188.8.131.52.
eth1 has 8000 aliases - eth1:1 to eth1:8000 with IP addresses 10.30.31.1 to 10.30.62.64 respectively.
Each of the eth1 aliases will emulate a virtual phone and are required to register/communicate with a Communications Server which is 148.147.143.XXX. This communication will be over a corporate LAN.
- NOTE: The corporate LAN (148.147.XXX.XXX) does not have a route to 10.30.XXX.XXX and this cannot be done owing to network policies and security.
- NOTE: No configuration changes are possible on the Communications Server (148.147.143.xxx).
Phone 8000 ---eth1:8000
Phone 3 ---eth1:3
Phone 2 ---eth1:2
Phone 1 ---eth1:1----CentOS Server
(10.30.31.1) eth1 << 10.30.30.
eth0 >> 148.148.134.XXX----LAN----148.147.143.XXX
My current routing table -
[root@XXXXXXXXX ~]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.30.30.0 * 255.255.255.0 U 0 0 0 eth1
184.108.40.206 * 255.255.255.0 U 0 0 0 eth0
169.254.0.0 * 255.255.0.0 U 0 0 0 eth1
10.16.0.0 * 255.240.0.0 U 0 0 0 eth1
default 220.127.116.11 0.0.0.0 UG 0 0 0 eth0
The virtual phones on the eth1 aliases (10.30.31.XXX - 10.30.62.XXX) are unable to register with the Communications Server (148.147.143.XXX). A successful registration will require 4 protocol messages to take place between the phone and the server. This is not happening at the moment.
Is it possible to get this working by using iptables/NAT or any other configuration on the CentOS server?
What I tried so far:
- Enabled IP forwarding.
- Tried some iptables rules, confusing and didnt work, so flushed them all.