Private LAN IP addresses
These IP addresses are reserved for private networks (sometimes called localnet). These are routable only in a LAN; WAN gateways will not route the following IP addresses. The 192.168.0.0/16 range is the most familiar. Often forgotten is the 172.16.0.0/12 range.
|IANA Reserved Private Network Ranges||Start of range||End of range||Total addresses|
|24-bit Block (/8, 1 x A)||10.0.0.0||10.255.255.255||16777216|
|20-bit Block (/12, 16 x B)||172.16.0.0||172.31.255.255||1048576|
|16-bit Block (/16, 256 x C)||192.168.0.0||192.168.255.255||65536|
|Link-local Zeroconf (/16 minus the first and last /24 ranges)||169.254.1.0||169.254.254.255||65026|
A regex to match an arbitrary IPv4 address can be quite tricky. The following get close for testing against private IP addresses.
# localhost allow ^127\.0\.0\.1$ # localnets # 192.168.0.0/16 allow ^192\.168\.\d+\.\d+$ # 172.16.0.0/12 allow ^172\.(1[6-9]|2[0-9]|3)\.\d+\.\d+$ # 10.0.0.0/8 allow ^10\.\d+\.\d+\.\d+$ # Link-local Zeroconf (/16 minus the first and last /24 ranges) # WARNING: this should exclude the first and last /24 ranges, but it does not. # This shouldn't matter since the first and last /24 ranges are reserved. allow ^169\.254\.\d+\.\d+$