To find the LAN IP address, open a shell and run:
ifconfig -a
Look for the inet addr in the output, which will look like below:
en0: flags=5e080863,c0
inet 172.17.188.74 netmask 0xfffffe00 broadcast 172.17.189.255
tcp_sendspace 131072 tcp_recvspace 65536
lo0: flags=e08084b
inet 127.0.0.1 netmask 0xff000000 broadcast 127.255.255.255
inet6 ::1/0
tcp_sendspace 131072 tcp_recvspace 131072 rfc1323 1