PuTTY wish kerberos-gssapi

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summary: Support for GSSAPI (for Kerberos, GSI, etc)
class: wish: This is a request for an enhancement.
difficulty: taxing: Needs external things we don't have (standards, users etc)
priority: low: We aren't sure whether to fix this or not.
fixed-in: r8952 99fffd6ed357d25a228637be173e8187746b6b77 2010-05-20 (0.61)

We occasionally get requests for Kerberos and/or GSSAPI support.

This looks complicated and messy.

Any proposed solution should take into account our design guidelines to be even considered for inclusion. In particular, some submissions have not taken into account PuTTY's cross-platform nature.

In SSH-2, Kerberos is supported through GSSAPI; RFC 4462 (formerly draft-ietf-secsh-gsskeyex) describes GSSAPI key exchange and user authentication in SSH-2. (Some of the patches here appear to be based on earlier versions of this specification, for instance the userauth method "gssapi".)

It appears that Globus GSI authentication also uses GSSAPI, though for some reason needs a different client implementation (and yet a third if you want to support both).

Patches we've seen (links are on our Links page):

Certified Security Solutions have a patched version of PuTTY which supports Kerberos 5 in SSH-1 and GSSAPI key exchange and user authentication in SSH-2. For GSSAPI, Win9x/NT require the MIT Kerberos library; Win2K/XP can use Microsoft SSPI.
Another patch (unreviewed): 1067597353.3fa23e29bf70c@webmail.technion.ac.il
User authentication; secur32.lib (Windows) / krb5-config (Unix)
Another patch from sweb.cz adds support for GSSAPI user authentication using the MIT Kerberos library. (A previous version of this patch has been reviewed and found wanting.)
Yet another patch: Quest PuTTY (formerly Vintela PuTTY)
3-term BSD licence; GSSAPI (Kerberos-specific?) user authentication using MS SSPI; not thoroughly reviewed but doesn't look hopeful

Binary-only versions:

Centrify provide a modified version of PuTTY which uses the Windows SSPI for GSSAPI support. It includes features specific to their other products.

Update: some forms of Kerberos support are now implemented:

As of 2008-08-10, r8138: support for Kerberos user authentication in SSH-2 using a single library (SSPI in Windows, build-time choice on Unix);
As of 2010-05-20, r8952: support for multiple libraries with choice at run time; Windows builds now support MIT Kerberos in addition to SSPI.

Things not done:

GSSAPI key exchange [implemented much later, see gss-key-exchange];
Any authentication protocol other than Kerberos;
SSH-1 support (we are very unlikely to do anything about this; SSH-1 is obsolete).

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Audit trail for this wish.

(last revision of this bug record was at 2018-05-20 14:07:14 +0100)