I'm trying to use EAP and DHCP together: EAP authenticates the client, the MAC address is stored to database along with username, and then the DHCP module looks up the MAC and uses it as a key to retrieve the username, which will be used to find the user group, which will be the ip pool for the address. Anyway, the problem I've found is that the device I'm using sends the Calling-Station-Id as uppercase separated with hyphen: AA-BB-CC-DD-EE-FF, while DHCP uses the lowercase-colon format: aa:bb:cc:dd:ee:ff. How can I normalize the formats before writing to database? I've found the "tolower" case function which solves half the problem. But I can't find a way to convert "-" into ":". I could do it on SQL but I'd rather do it on Freeradius before it's stored. Maybe even a more minimalistic format would be better for MAC address: all lowercase, no separators: aabbccddeeff. A simple regex could discard anything that's not 0123456789abcdef, and then convert to lowercase. Thanks, Hernan