Max length for client ip address [duplicate]

Answer 1

If you want to handle IPV6 in standard notation there are 8 groups of 4 hex digits:

2001:0dc5:72a3:0000:0000:802e:3370:73E4

32 hex digits + 7 separators = 39 characters.

CAUTION: If you also want to hold IPV4 addresses mapped as IPV6 addresses, use 45 characters as @Deepak suggests.

Answer 2

If you are just storing it for reference, you can store it as a string, but if you want to do a lookup, for example, to see if the IP address is in some table, you need a "canonical representation." Converting the entire thing to a (large) number is the right thing to do. IPv4 addresses can be stored as a long int (32 bits) but you need a 128 bit number to store an IPv6 address.

For example, all these strings are really the same IP address: 127.0.0.1, 127.000.000.001, ::1, 0:0:0:0:0:0:0:1