Subject: Problem reaching public internet from private address inside a VPS
From:Víctor Román Archidona <daijo@unixevil.info>
Date: Thu, 27 Mar 2008 10:44:19 +0100
Thu, 27 Mar 2008 10:44:19 +0100
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Hi,

I'm using several VPS on the same machine with multiple public IP
addresses. Both host and VPS machines has network conectivity and reachs
the public Internet via eth0, which has all the public IPs.

Now I'm building "private" VPS on 172.16.1.0/24 network segment. If I
give 172.16.1.1 to HOST and 172.16.1.10 to a private VPS, they both can
see each other.

The problem comes when I try to reach the public internet from the
private VPS on the private subnet. I also enabled forwarding and
postrouting on the host:

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -s 172.16.1.0/24 ! -d 172.16.1.0/24 -j
SNAT --to A.B.C.D

(being A.B.C.D the public IP address).

The VPS has the following interfaces configuration:
~ /etc/vservers/private/interfaces/0/dev    > lo
~ /etc/vservers/private/interfaces/0/prefix > 8
~ /etc/vservers/private/interfaces/0/ip     > 127.0.0.1

~ /etc/vservers/private/interfaces/1/dev    > eth0
~ /etc/vservers/private/interfaces/1/prefix > 24
~ /etc/vservers/private/interfaces/1/ip     > 171.16.1.10

Can anyone help me or give some hint about why I cannot reach the public
Internet?

Regards,
- --
Victor Roman Archidoan
http://blog.daijo.org
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