Return-Path: Received: from mail-yw0-f172.google.com ([209.85.161.172]:34380 "EHLO mail-yw0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756444AbcKBQyP (ORCPT ); Wed, 2 Nov 2016 12:54:15 -0400 Received: by mail-yw0-f172.google.com with SMTP id t125so13660787ywc.1 for ; Wed, 02 Nov 2016 09:54:14 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: Olga Kornievskaia Date: Wed, 2 Nov 2016 12:54:13 -0400 Message-ID: Subject: Re: gss context cache and nfsv4 To: Matt Garman Cc: linux-nfs Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, Nov 2, 2016 at 10:03 AM, Matt Garman wrote: > On Wed, Aug 31, 2016 at 2:41 PM, Olga Kornievskaia wrote: >> I should have asked for what distro/nfs-utils are you using? >> >> In the RHEL/Fedora nfs-utils distros, lifetime of the context is >> gotten from gss_inquire_context() call from the gss krb5 api. In >> krb5_gss_inquire_context() in krb5 source code in >> src/lib/gssapi/krb5/inq_context.c it's set to what I have set before. >> >> A server can choose to expire the context at any time by returning gss >> context error and force the client to create the new security context. >> What server are you going against? A network trace would be helpful to >> check to see if the server is returning such error. > > Bringing this thread back to life... > > I am using CentOS (effectively same as RHEL) 6.5. nfs-utils version > 1.2.3-39. All clients and servers are same OS version, same kernel, > same nfs-utils. That's like way way way old.. but shouldn't really matter i guess > Just to be clear: in your suggestion of a network trace, do you mean > using something like tcpdump or wireshark to see exactly what is going > on between client and server? Is it sufficient to do this while I am > seeing "permission denied" on the krb5p share? Yes tcpdump or wireshark and yes during the failure. I'm suspecting that the server is returning the error that it has expired the context. That you should be able to see even if it's krb5p mount. You should look for rpc.authgss.major != 0 for your filter. > Since I am using krb5p (not the 'p'), I believe all NFS traffic is > encrypted... so will I actually be able to see anything useful in the > packet capture? Can you elaborate specifically on what I should look > for? > > Lastly... as a workaround, can I use the "-t" parameter of rpc.gssd? > What if I set that value to be equivalent to be the same as our > Kerberos ticket lifetime? If the server is deciding the expire the context there is no work around. > Thank you, > Matt