[22250] in Kerberos
Re: GSSAPI security for connection encryption
daemon@ATHENA.MIT.EDU (Jeffrey Altman)
Thu Aug 19 19:01:55 2004
Message-ID: <41253057.3000907@nyc.rr.com>
From: Jeffrey Altman <jaltman2@nyc.rr.com>
Date: Thu, 19 Aug 2004 22:56:10 GMT
To: kerberos@mit.edu
Errors-To: kerberos-bounces@mit.edu
FTP AUTH GSS cannot be implemented with SEQUENCE protection if
the client plans on sending data on the command channel while
there is an active data channel using the GSS context. This is
a serious problem for GUI FTP implementations which issue
STAT commands for status updates; or for other implementation
wishing to protect against NAT/firewall timeouts.
I have a proposal to fix this but the changes are incompatible
with the current implementation. Hopefully I will find the
time to work on submitting it to the IETF.
Jeffrey Altman
Markus Moeller wrote:
> The MIT ftp client uses only the REPLAY flag, which I think should be
> changed to the SEQUENCE FLAG to provide the correct protection for the data
> channel.
>
> gss_init_sec_context(&min_stat,
> GSS_C_NO_CREDENTIAL,
> &gcontext,
> target_name,
> (gss_OID_desc *)gss_trials[trial].mech_type,
> GSS_C_MUTUAL_FLAG | GSS_C_REPLAY_FLAG |
> (forward ? GSS_C_DELEG_FLAG :
> (unsigned) 0),
> 0,
> &chan, /* channel bindings */
> token_ptr,
> NULL, /* ignore mech type */
> &send_tok,
> NULL, /* ignore ret_flags */
> NULL); /* ignore time_rec */
>
>
> Will I get problems with the SEQUENCE FLAG if I want to send a NOOP on the
> command channel during a transfer happens on the data channel (.e.g. to keep
> to command channel open through firewalls ) as the client and server have to
> process the data in sync which is not necessarily given ?
>
> Thanks
> Markus
>
> "Sam Hartman" <hartmans@MIT.EDU> wrote in message
> news:tslzn4qssps.fsf@cz.mit.edu...
>
>>>>>>>"Markus" == Markus Moeller <huaraz@moeller.plus.com> writes:
>>
>> Markus> will Sequence protection (GSS_C_SEQUENCE_FLAG)cover replay
>> Markus> protection (GSS_C_REPLAY_FLAG) as well or are there cases
>> Markus> were I need both ?
>>
>>I'd recommend using both, but I believe sequence is typically a
>>superset.
>>
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>
>
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