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I have a server with a public IP in eth0 and routed network config.

I have created DomUs with private IPs (10.0.1.x) and they can ping Dom0 and other private IPs, however I want them to ping the outer world.

How can I achieve this?

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up vote 0 down vote accepted

After some research, here are the commands to be executed on the Dom0. Replace $VIF_NAME with the virtual interface name of your Xen VM.

Add forwarding

iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
iptables -A FORWARD -o eth0 -i $VIF_NAME -j ACCEPT
iptables -A FORWARD -o $VIF_NAME -i eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT

Remove forwarding

IDS=$(iptables -L FORWARD -nv --line-numbers | grep "$VIF_NAME" | cut -d' ' -f1 | sort -r)
for id in $IDS; do
  iptables -D FORWARD $id
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