Failure of SIP Proxy Authentication

Question

I'm developing a SIP user agent application that connects to an Asterisk server and tries to do an outgoing call. I'm using the NIST implementation of the JAIN SIP API.

When the application registers itself, a 401 (Unauthorized) response challenges it with a WWW-Authenticate header. The application inserts the Authorization header into the next REGISTER request. This time Asterisk returns a 200 (OK) response - the registration is successful.

When the application transmits an INVITE request, Asterisk responds with a 407 (Proxy Authentication Required) response. This time the response contains a Proxy-Authenticate header. My application sends an INVITE again, but this time with the Authorization header, upon which Asterisk responds with the same 407 (Proxy Authentication Required) response.

Here are the SIP messages that are transmitted ('>>' indicates outgoing messages; '<<' indicates incoming messages):

>>

REGISTER sip:10.0.84.30:5060 SIP/2.0
Call-ID: acf3c0e9c1338d2c28d9c534ae86cbd8@10.0.85.3
CSeq: 1 REGISTER
From: <sip:301@asterisk>;tag=2B3n8g
To: <sip:301@asterisk>
Via: SIP/2.0/UDP 10.0.85.3:5060;branch=z9hG4bKc7dd178d3d444ccc059a191e700fc8b73230
Max-Forwards: 70
Contact: <sip:10.0.85.3:5060>
Expires: 300
Content-Length: 0

<<

SIP/2.0 100 Trying
Via: SIP/2.0/UDP 10.0.85.3:5060;branch=z9hG4bKc7dd178d3d444ccc059a191e700fc8b73230;received=10.0.85.3
From: <sip:301@asterisk>;tag=2B3n8g
To: <sip:301@asterisk>
Call-ID: acf3c0e9c1338d2c28d9c534ae86cbd8@10.0.85.3
CSeq: 1 REGISTER
User-Agent: Asterisk PBX (switchvox)
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,SUBSCRIBE,NOTIFY
Contact: <sip:301@10.0.84.30>
Content-Length: 0

<<

SIP/2.0 401 Unauthorized
Via: SIP/2.0/UDP 10.0.85.3:5060;branch=z9hG4bKc7dd178d3d444ccc059a191e700fc8b73230;received=10.0.85.3
From: <sip:301@asterisk>;tag=2B3n8g
To: <sip:301@asterisk>;tag=as3c458716
Call-ID: acf3c0e9c1338d2c28d9c534ae86cbd8@10.0.85.3
CSeq: 1 REGISTER
User-Agent: Asterisk PBX (switchvox)
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,SUBSCRIBE,NOTIFY
Contact: <sip:301@10.0.84.30>
WWW-Authenticate: Digest realm="asterisk",nonce="6fbe5a68"
Content-Length: 0

>>

REGISTER sip:10.0.84.30:5060 SIP/2.0
CSeq: 2 REGISTER
From: <sip:301@asterisk>;tag=2B3n8g
To: <sip:301@asterisk>
Via: SIP/2.0/UDP 10.0.85.3:5060;branch=z9hG4bKffb0be254f93f61fa0dc7ac32b9078a43230
Max-Forwards: 70
Contact: <sip:10.0.85.3:5060>
Expires: 300
Authorization: Digest username="301",realm="asterisk",nonce="6fbe5a68",response="bc7075e8e241a4109dfa24d6ae95e78c",algorithm=MD5,uri="sip:10.0.84.30:5060",nc=00000001
Call-ID: acf3c0e9c1338d2c28d9c534ae86cbd8@10.0.85.3
Content-Length: 0

<<

SIP/2.0 100 Trying
Via: SIP/2.0/UDP 10.0.85.3:5060;branch=z9hG4bKffb0be254f93f61fa0dc7ac32b9078a43230;received=10.0.85.3
From: <sip:301@asterisk>;tag=2B3n8g
To: <sip:301@asterisk>
Call-ID: acf3c0e9c1338d2c28d9c534ae86cbd8@10.0.85.3
CSeq: 2 REGISTER
User-Agent: Asterisk PBX (switchvox)
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,SUBSCRIBE,NOTIFY
Contact: <sip:301@10.0.84.30>
Content-Length: 0

<<

SIP/2.0 200 OK
Via: SIP/2.0/UDP 10.0.85.3:5060;branch=z9hG4bKffb0be254f93f61fa0dc7ac32b9078a43230;received=10.0.85.3
From: <sip:301@asterisk>;tag=2B3n8g
To: <sip:301@asterisk>;tag=as3c458716
Call-ID: acf3c0e9c1338d2c28d9c534ae86cbd8@10.0.85.3
CSeq: 2 REGISTER
User-Agent: Asterisk PBX (switchvox)
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,SUBSCRIBE,NOTIFY
Expires: 300
Contact: <sip:10.0.85.3:5060>;expires=300
Date: Tue, 03 May 2011 06:42:33 GMT
Content-Length: 0

>>

INVITE sip:302@asterisk SIP/2.0
Call-ID: c20df277bb6f9fb69d83000e5255eb86@10.0.85.3  
CSeq: 3 INVITE
From: <sip:301@asterisk>;tag=KOZWxg
To: <sip:302@asterisk>
Via: SIP/2.0/UDP 10.0.85.3:5060;branch=z9hG4bKaa0520efde83907b71d1f76315188c413230
Max-Forwards: 70
Contact: <sip:10.0.85.3:5060>
Route: <sip:10.0.84.30:5060;lr>
Content-Type: application/sdp
Content-Length: 106

>>

v=0
o=- 3513393083 3513393083 IN IP4 10.0.85.3
s=-
c=IN IP4 10.0.85.3
t=0 0
m=audio 40000 RTP/AVP 3

<<

SIP/2.0 407 Proxy Authentication Required
Via: SIP/2.0/UDP 10.0.85.3:5060;branch=z9hG4bKaa0520efde83907b71d1f76315188c413230;received=10.0.85.3
From: <sip:301@asterisk>;tag=KOZWxg
To: <sip:302@asterisk>;tag=as5de9ed83
Call-ID: c20df277bb6f9fb69d83000e5255eb86@10.0.85.3
CSeq: 3 INVITE
User-Agent: Asterisk PBX (switchvox)
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,SUBSCRIBE,NOTIFY
Contact: <sip:302@10.0.84.30>
Proxy-Authenticate: Digest realm="asterisk",nonce="74986b64"
Content-Length: 0

>>

INVITE sip:302@asterisk SIP/2.0
CSeq: 4 INVITE
From: <sip:301@asterisk>;tag=2B3n8g
To: <sip:302@asterisk>
Via: SIP/2.0/UDP 10.0.85.3:5060;branch=z9hG4bK86f9dbdff9eeca422fbb67321dd45f7a3230
Max-Forwards: 70
Contact: <sip:10.0.85.3:5060>
Route: <sip:10.0.84.30:5060;lr>
Content-Type: application/sdp
Authorization: Digest   username="301",realm="asterisk",nonce="74986b64",response="a08b8d7ce96cae00e7d334e132bf7358",algorithm=MD5,uri="sip:302@asterisk",nc=00000001
Call-ID: acf3c0e9c1338d2c28d9c534ae86cbd8@10.0.85.3
Content-Length: 106

>>

v=0
o=- 3513393083 3513393083 IN IP4 10.0.85.3
s=-
c=IN IP4 10.0.85.3
t=0 0
m=audio 40000 RTP/AVP 3

<<

SIP/2.0 407 Proxy Authentication Required
Via: SIP/2.0/UDP 10.0.85.3:5060;branch=z9hG4bK86f9dbdff9eeca422fbb67321dd45f7a3230;received=10.0.85.3
From: <sip:301@asterisk>;tag=2B3n8g
To: <sip:302@asterisk>;tag=as3c458716
Call-ID: acf3c0e9c1338d2c28d9c534ae86cbd8@10.0.85.3
CSeq: 4 INVITE
User-Agent: Asterisk PBX (switchvox)
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,SUBSCRIBE,NOTIFY
Contact: <sip:10.0.85.3:5060>
Proxy-Authenticate: Digest realm="asterisk",nonce="1bd30f50"
Content-Length: 0

The Authorization header is constructed in exactly the same way in both cases (same code that is executed). I'm using the request's request-URI for "digestURI". I've tried using a Proxy-Authorization header instead of an Authorization header, but the result is the same.

Can anyone see what I'm doing wrong? Thanks in advance.

Answer 1

For authenticating to a proxy (in other words you got a 407 Proxy Authentication Required you need a Proxy-Authorization header.

As RFC 2617 says, you construct this in the same way as you would an Authorization header.

You mention using the From URI in your question. RFC 2617 section 3.2.2 says you use the Request-URI (sip:302@asterisk). Watch out for the SIP-specific changes in RFC 3261 section 22.4.

Answer 2

I've solved the problem. It seems that Asterisk could not associate my second INVITE request to the preceding 407 (Proxy Authentication Required) response, containing the nonce value for the Proxy-Authentication header.

This was because I didn't use the same values for Call-ID and the tag of the From-header for the two INVITE requests. For the second INVITE request, which contains the Proxy-Authentication Header, I've accidentally used the Call-ID and From-header tag values of the first REGISTER request, instead of the first INVITE request.

The INVITE does not yet succeed, though. For the second response I now get 488 (Not acceptable here), but I will try to find out what is wrong now in a different question.

Answer 3

It's s bit strange that your Asterisk server is responding with a 407 I just checked mine and it responds with 401. Asterisk is after all a B2BUA rather than a proxy. I'd recommend trying an Authorization header in the authenticated request rather than Proxy-Authorization as that works with my Asterisk server.

Also you need to use the request URI in the digest and not the From header URI. So in your case it should be uri=sip:302@asterisk.