Hello,

i have an CentOS (Redhat) Linux server and on it is installed OpenVZ which allows creating virtual machines there.

Now to my CentOS host server is pointed a few IP-RIPE addresses, these IPs are mentioned in several domains nameservers, i want to migrate virtual machines to another server and my question is how i can achieve that websites which domains pointing to old server will resolve and work and load from a new server? (meaning there will be redirection on server which redirect old ip request to a new IP of new server) If it would be possible, redirecting all kind of requests, but for simplicity, HTTP most important

Thank you

You could use a dnat rule and masquerade in iptables to do the redirect.

iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination <new_ip>:80
iptables -t nat -A POSTROUTING -p tcp --dport 80 -d <new_ip> -j MASQUERADE

You'll have to turn on forwarding as well. Usually there is a sysctl.conf file you can turn it on permanently in (/etc/sysctl.conf). The entry will look something like net.ipv4.ip_forward=1

You can turn it on temporarily by doing: echo 1 > /proc/sys/net/ipv4/ip_forward

thanks, your IP tables rules should be done probably on each Virtual Machine.

i meant to do it from VM host server, but such iptables rule would need to contain probably two IPs, old and new.. each rule for each VM? Is it possible to do from host server, how such command can look like?

Those rules only need to be done on the server that originally hosted the service.

With regards to using the VM host server. If it has the original (old) ip then the rules would go on it. If those ips are externally routable then easiest would probably be to update your dns to use the new ips.

You'd need a rule for each service you were redirecting, the only thing that'd change is the port and new ip