Networking vserver guests
Setting up network access to and from your vserver guests.
Lets imagine, you have only one external IP --
You want to have several vservers running without worrying about port overlapping.
Two vservers run a default webserver, running on port 80. If each "guest" vserver shares an IP with the host, then the two webservers will conflict.
One solution is:
- All vservers are contained in a "virtual lan", say 192.168.1.x
- Each vserver has its own IP
- Control port forwarding on "parent" host. That is, run a router.
First you need to load the dummy interface driver
# modprobe dummy
To have it automatically loaded on startup, add "loopback" to /etc/modules
dummy0 interface on the parent host
# /etc/network/interfaces on a Debian box, # configure on other distros with your preferred way auto dummy0 iface dummy0 inet static address 192.168.1.250 netmask 255.255.255.0
Set up each guest vserver:
cd /etc/vservers/$VSERVER/interfaces/0 echo dummy0 > dev echo 192.168.1.1 > ip echo 1 > name echo 24 > prefix
Consider using a value of
name equal to the last digit of the IP for easy separation.
Host as router
Configure the host to act as a router.
For internal packets going outside, pretend each packet came from our external IP (put it in one line without backslash):
# iptables -t nat -A POSTROUTING -s 192.168.1.0/24 \ -d ! 192.168.1.0/24 -j SNAT --to-source $EXTIP
For each service that runs on a vserver, map it to an external port. Vserver local address
$VHOST and port
$INTPORT you select one external port
$EXTPORT and run the following (put it in one line without backslash):
# iptables -t nat -A PREROUTING -s ! 192.168.1.0/24 \ -m tcp -p tcp --dport $EXTPORT -j DNAT --to-destination $VHOST:$INTPORT
ping pool.ntp.org from your vserver -- it should ping fine.
Try to connect to your
$EXTIP:$EXTPORT (from another external host) -- you will successfully connect to service running on a guest vserver.