Access-Accept format & Error sending request: No valid RADIUS responses received

[sotmg]

I didn't find any section for programming so I am posting this here.

I have enabled captive portal in pfSense and all settings are OK, the internet is connected and works with the User Manager. Now I have enabled RADIUS on default port and with no shared secret.

I made a small program for my small network, it listens to connections on UDP 1812, which works fine, I get the Access-Request packet and use it to get information about the client, but when I send back the Access-Accept packet it get discarded I think.

I read the following pages to learn the packet format:
http://technet.microsoft.com/en-us/library/cc958030.aspx
http://rfc-ref.org/RFC-TEXTS/2865/chapter3.html
and a few more.

Access-Accept packet format:
byte 0    == Code 2
byte 1    == Identifier (same as Access-Request packet)
byte 2-3  == Length of this packet (always 20 bytes)
byte 4-20 == MD5 hash of this packet's first 4 bytes and Access-Request's Authenticator bytes

20 bytes total.

pfSense returns: "Error sending request: No valid RADIUS responses received "

[sotmg]

Incase someone asks why am I doing this and not <something else="">, it is because I am trying something and I finished it, only this last step remains, sending Access-Accept packet.</something>