Does freeradius-client library support CHAP protocol?

Tarkshya tarkshya at
Mon Apr 20 20:50:43 CEST 2009

Hello all,

I tried to enable CHAP protocol support in the freeradius-client
library by uncommenting the CHAP code in sendserver.c file. (It is the
code which was blocked using #if 0 macro) However, when I send a chap
password, the server rejects the request saying that

Found Auth-Type = CHAP
+- entering group CHAP {...}
[chap] rlm_chap: password supplied has wrong length

What could be wrong here?

Also, apparently the radclient testing tools which comes with
freeradius SERVER can successfully authenticate using CHAP passwords.
Its only the client tool (radiusclient) that gives problem. I noticed
that the logic of encoding CHAP passwords is different in freeradius
client and free radius server code.

Can somebody give me the exact algorithm for encoding and sending CHAP
passwords in radius packets.


On Thu, Apr 2, 2009 at 5:17 AM, Alan DeKok <aland at> wrote:
> Tarkshya wrote:
>> I am going to build CHAP support in the freeradius client library. My
>> question is, does freeradius server at least support CHAP?
>  Yes.
>> Does anybody know any other radius servers that support CHAP, and
>> possibly MS-CHAP too.
>  I'd be surprised if any RADIUS server *doesn't* support CHAP and MS-CHAP.
>  Alan DeKok.
> -
> List info/subscribe/unsubscribe? See

More information about the Freeradius-Devel mailing list