Mediant 2000 SIPMediant 2000 SIP User’s Manual 156 Document #: LTRT-725048.12 SIP Authentication ExampleMediant 2000 gateway supports basic and digest authentication types, according to SIP RFC3261 standard. A proxy server might require authentication before forwarding an INVITEmessage. A Registrar/Proxy server may also require authentication for client registration. A proxyreplies to an unauthenticated INVITE with a 407 Proxy Authorization Required response,containing a Proxy-Authenticate header with the form of the challenge. After sending an ACK forthe 407, the User Agent can then resend the INVITE with a Proxy-Authorization headercontaining the credentials.User Agent, Redirect or Registrar servers typically use 401 Unauthorized responses to challengeauthentication containing a WWW-Authenticate header, and expect the re-INVITE to contain anAuthorization header.The following example describes the Digest Authentication procedure including computation ofUser Agent credentials.The REGISTER request is sent to Registrar/Proxy server for registration, as follows:REGISTER sip:10.2.2.222 SIP/2.0Via: SIP/2.0/UDP 10.1.1.200From: 122@10.1.1.200>;tag=1c17940To: 122@10.1.1.200>Call-ID: 634293194@10.1.1.200User-Agent: Audiocodes-Sip-Gateway/TrunkPack 1610/v.4.20.299.412CSeq: 1 REGISTERContact: sip:122@10.1.1.200:Expires:3600On receiving this request the Registrar/Proxy returns 401 Unauthorized response.SIP/2.0 401 UnauthorizedVia: SIP/2.0/UDP 10.2.1.200From: >;tag=1c17940To: >Call-ID: 634293194@10.1.1.200Cseq: 1 REGISTERDate: Mon, 30 Jul 2001 15:33:54 GMTServer: Columbia-SIP-Server/1.17Content-Length: 0WWW-Authenticate: Digest realm="audiocodes.com",nonce="11432d6bce58ddf02e3b5e1c77c010d2",stale=FALSE,algorithm=MD5According to the sub-header present in the WWW-Authenticate header the correct REGISTERrequest is formed.Since the algorithm used is MD5, take:The username from the ini file: M2K-AudioCodesThe realm return by the proxy: audiocodes.comThe password from the ini file: AudioCodes.The equation to be evaluated: (according to RFC this part is called A1).“M2K-AudioCodes:audiocodes.com:AudioCodes”.The MD5 algorithm is run on this equation and stored for future usage.The result is: “a8f17d4b41ab8dab6c95d3c14e34a9e1”Next we need to evaluate the par called A2. We take:The method type “REGISTER”
