In some installations, AstLinux will not be your LAN's gateway, and AstLinux itself might have to use a gateway to reach a particular subnet (common in VPN situations). To configure this, edit /mnt/kd/rc.elocal (or create it, if not yet present, and make it executable), and add the following to it:
ip route add to xxx.xxx.xxx.xxx/xx via yyy.yyy.yyy.yyy dev ethz
xxx.xxx.xxx.xxx/xx is the remote subnet which can be reached via the gatewayyyy.yyy.yyy.yyy is the IP address of the gatewayethz is the NIC attached to the same subnet as the gateway
rc.elocal is simply a start-up script which runs directly after the network startup script.