func setupIPTables(bridgeName, natIface string) error {
nat := []string{"POSTROUTING", "-t", "nat", "-o", natIface, "-j", "MASQUERADE"}
if !iptables.Exists(nat...) {
if output, err := iptables.Raw(append([]string{"-I"}, nat...)...); err != nil {
return fmt.Errorf("unable to enable network bridge NAT: %s", err)
} else if len(output) != 0 {
return fmt.Errorf("unknown error creating bridge NAT rule: %s", output)
}
}
forward := []string{"FORWARD", "-i", bridgeName, "-j", "ACCEPT"}
if !iptables.Exists(forward...) {
if output, err := iptables.Raw(append([]string{"-I"}, forward...)...); err != nil {
return fmt.Errorf("unable to enable forwarding: %s", err)
} else if len(output) != 0 {
return fmt.Errorf("unknown error enabling forwarding: %s", output)
}
}
return nil
}
func cleanupIPTables(bridgeName string) {
// Delete the forwarding rule. The postrouting rule does not need deletion
// as there is usually only one per box and it doesn't change.
iptables.Raw("-D", "FORWARD", "-i", bridgeName, "-j", "ACCEPT")
}