TechInfoDepot:DD-WRT/Private ip address

Private internet addresses are often used on the LAN.

The allowed private IPv4 addresses are specified in rfc1918:
 * 10.0.0.0       -   10.255.255.255  (10/8 prefix)
 * 172.16.0.0     -   172.31.255.255  (172.16/12 prefix)
 * 192.168.0.0    -   192.168.255.255 (192.168/16 prefix)

Note: Private ip addresses must be (source) translated (NATted, tcp, udp: PAT) to a public (=non-private) ip address (tcp: socket) before its payload can be send into the (public) internet.