krb5_rd_cred checks IP address.

Nicolas Williams Nicolas.Williams at
Fri Feb 8 11:31:10 EST 2002

On Fri, Feb 08, 2002 at 08:15:28AM -0800, Booker C. Bense wrote:
> On Thu, 7 Feb 2002, Sam Hartman wrote:
> > I'm not really sure what good this check does other than to screw over
> > NAT users.  Even if we pretend that we actually still care about IP
> > address authentication what is the harm of accepting tickets from
> > someone provided that they work?
> - I can't see one. The whole rational for the IP check is to make
> replay attacks harder, but I don't grok how that would even apply
> in this situation.

I thought limiting the use of stolen creds was one of the rationales for
having those IP address checks... Of course, if you steal forwardable
creds you probably have access to the host where they must be used and
then you can do whatever you want...

> >
> > I'm really not sure how to go about fixing this problem.  I could see
> > solving in several ways and am not sure which one the community
> > prefers.  Do we remove the check on the source address?
> - I would vote for this option. The IP checks have always seemed to
> me to be the wrong solution to replay attacks, it doesn't really
> solve the problem. A session key cache does.
> - Booker C. Bense

-DISCLAIMER: an automatically appended disclaimer may follow. By posting-
-to a public e-mail mailing list I hereby grant permission to distribute-
-and copy this message.-

Visit our website at

This message contains confidential information and is intended only 
for the individual named.  If you are not the named addressee you 
should not disseminate, distribute or copy this e-mail.  Please 
notify the sender immediately by e-mail if you have received this 
e-mail by mistake and delete this e-mail from your system.

E-mail transmission cannot be guaranteed to be secure or error-free 
as information could be intercepted, corrupted, lost, destroyed, 
arrive late or incomplete, or contain viruses.  The sender therefore 
does not accept liability for any errors or omissions in the contents 
of this message which arise as a result of e-mail transmission.  If 
verification is required please request a hard-copy version.  This 
message is provided for informational purposes and should not be 
construed as a solicitation or offer to buy or sell any securities or 
related financial instruments.

More information about the krbdev mailing list