Openvpn Server with Virtual Interfaces

pada123

Good day all .
I have Openvpn Server installed in a Linux server and I can access Internet through it

I have 2 Public IPs
( Physical )eth0 - xxx.xxx.xxx.xxx
eth0:1 - yyy.yyy.yyy.yyy

[real ip changed]

I can run server(Bind) on both IP and from my desktop I can connect to openvpn server on both IPs

But the problem is if I run openvpn server in yyy.yyy.yyy.yyy and from my desktop if i open ip2location dot com or similar site it reports IP - xxx.xxx.xxx.xxx in my browser.

because I forward it to eth0 which has IP - xxx.xxx.xxx.xxx

iptables -t nat -A POSTROUTING -s 172.18.0.0/24 -o [b]eth0  [/b]-j MASQUERADE

So I need to have something like following

iptables -t nat -A POSTROUTING -s 172.18.0.0/24 -o [b]eth0:1  [/b]-j MASQUERADE

so that outgoing packet from my box has source IP [ eth0:1 - yyy.yyy.yyy.yyy ] so that those site can report IP as
yyy.yyy.yyy.yyy.

But the problem is if I run

iptables -t nat -A POSTROUTING -s 172.18.0.0/24 -o [b]eth0:1  [/b]-j MASQUERADE

iptables -t nat -A POSTROUTING -s 172.18.0.0/24 -o [b]eth1  [/b]-j MASQUERADE

I can not access Internet at all.

Can you please focus some light.

Thank you

pada123

If anybody focus some light.

Thanks for your time.

Mimiko

Actually, after establishing a tunnel thru any public interface its hard to detect in iptables to which public interface belongs some incomming packet from tunnel. You have to setup second OpenVPN server, each one for every public interface. Also, revise the redirection you are doing. Othern then masquerading, you have to dinamically change internet gateway with iptables (--redirect-to).

pada123

Thank Mimiko for your input. I understand it.
As mentioned I have already two separate openvpn processes running on separate public address in same box.

But all outgoing packet src address ( say from my box to google.com ) always have the public IP of eth0.

So for users though they are given two IPs saying we have two openvpn servers running ..but checking with IP2LOCATION dot com will always return IP of eth0 in client browser.. making them believe only Single Openvpn server running.

Many Openvpn service providers run multiple openvpn processes in a single box and bind with separate public IP.
and it reports separate IP in browser when checked with ip2location dot com.

Can you please focus on ( --redirect-to as you mentioned ) or how to handle this situation.
Thank you again

pada123

Hi All,
Any body configured Openvpn server with eth0:1 , eth0:2 etc... with following scenario..
Can you please provide inputs.
Thanks
Pada

pada123

After digging it for a long time I am able to fix it ...

i Simply Replace following line

iptables -t nat -A POSTROUTING -s 172.21.0.0/24 -o eth0  -j MASQUERADE

with this one

iptables -t nat -A POSTROUTING -s 172.21.0.0/24   -o eth0  -j SNAT  --to-source IPOFETH1
iptables -t nat -A POSTROUTING -s 172.22.0.0/24   -o eth0  -j SNAT  --to-source IPOFETH2
iptables -t nat -A POSTROUTING -s 172.23.0.0/24   -o eth0  -j SNAT  --to-source IPOFETH3

Now I can 3 openvpn processes in a single box which reporting different different IPS when checked from users browser using ip2location dot com .

Hope it will help other who are trying to setup multiple openvpn process using 1 physical NIC and multiple virtual interfaces ....

Thanks