System information

Chapter 8 Customizing Services 129
Providing VPN Service Through an Internet Router
If your server provides VPN service through an AirPort Base Station or other Internet
router, and users’ computers need to make VPN connections through their own base
stations or Internet routers, your server must be on a different IP subnet than the VPN
users’ computers. In other words, your server’s IP address can’t begin with the same
three numbers as VPN users’ IP addresses, such as 10.0.1 or 192.168.1.
You can avoid this conflict by changing the third number of the IP address of all the
devices on your server’s local network—AirPort Base Station or other Internet router,
server, and other computers. Use a number between 2 and 254. For example, if your
server and other devices on its network have IP addresses that begin with “10.0.1,”
change them to begin with “10.0.2” or “10.0.100.” If their IP addresses begin with
“192.168.1,” you might change them to begin with “192.168.5” or “192.168.70.” You can
also use 172.16.0 through 172.31.255. In all cases, use subnet mask 255.255.255.0.
If your AirPort Base Station, other Internet router, or DHCP server assigns IP addresses
to computers on your network, change it to assign IP addresses that begin with the
same three numbers as the server’s IP address. If possible, make these changes before
setting up your server. You make these changes on an AirPort Base Station using
AirPort Utility (located in /Applications/Utilities/). For instructions, open AirPort Utility
and then use the Help menu. For information about configuring another kind of
Internet router or gateway, see its documentation.
For information about changing your server’s IP address, see “Changing Your Server’s IP
Address” on page 134.