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Cisco Bug: CSCtc17240 - SIP: nonce-count 'nc' hex values should be lowercase, RFC compliance

Last Modified

Feb 11, 2018

Products (1)

  • Cisco IOS

Known Affected Releases

12.4T 15.2(0.1)T 15.2(0.15)T

Description (partial)

Some third party SIP PBXs may have interoperability problems with the
authentication header of a Cisco SIP gateway.

Per RFC 3261 section 25.1, the "nc" value, or nonce-count, should
have lower case hex.

This is defined as follows:

nonce-count       =  "nc" EQUAL nc-value
nc-value          =  8LHEX

LHEX  =  DIGIT / %x61-66 ;lowercase a-f

A snippet of the offending messaging:
 ...  cnonce="305EE7FF",qop="auth",algorithm=MD5,nc=0000000A
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