rpc.gssd(8)

NAME
rpc.gssd - rpcsec_gss daemon

SYNOPSIS
rpc.gssd [-f] [-n] [-k keytab] [-p pipefsdir] [-v] [-r] [-d ccachedir]

DESCRIPTION
The rpcsec_gss protocol gives a means of using the gss-api generic security api to provide security for protocols using rpc (in particular, nfs). Before exchanging any rpc requests using rpcsec_gss, the rpc client must first establish a security context. The linux kernel's implementation of rpcsec_gss depends on the userspace daemon rpc.gssd to establish security contexts. The rpc.gssd daemon uses files in the rpc_pipefs filesystem to communicate with the kernel.

OPTIONS

-f  Runs rpc.gssd in the foreground and sends output to stderr (as opposed to syslogd)

-n  By default, rpc.gssd treats accesses by the user with UID 0 specially, and uses "machine credentials" for all accesses by that user which require Kerberos authentication. With the -n option, "machine credentials" will not be used for accesses by UID 0. Instead, credentials must be obtained manually like all other users. Use of this option means that "root" must manually obtain Kerberos credentials before attempting to mount an nfs filesystem requiring Kerberos authentication.

-k keytab
    Tells rpc.gssd to use the keys found in keytab to obtain "machine credentials". The default value is "/etc/krb5.keytab".

    Previous versions of rpc.gssd used only "nfs/*" keys found within the keytab. To be more consistent with other implementations, we now look for specific keytab entries. The search order for keytabs to be used for "machine credentials" is now:
      <HOSTNAME>$@<REALM>
      root/<hostname>@<REALM>
      nfs/<hostname>@<REALM>
      host/<hostname>@<REALM>
      root/<anyname>@<REALM>
      nfs/<anyname>@<REALM>
      host/<anyname>@<REALM>

    If this search order does not use the correct key then provide a keytab file that contains only correct keys.

-p path
    Tells rpc.gssd where to look for the rpc_pipefs filesystem. The default value is "/var/lib/nfs/rpc_pipefs".

-d directory
    Tells rpc.gssd where to look for Kerberos credential files. The default value is "/tmp". This can also be a colon separated list of directories to be searched for Kerberos credential files. Note that if machine credentials are being stored in files, then the first directory on this list is where the machine credentials are stored.

-v  Increases the verbosity of the output (can be specified multiple times).

-r  If the rpcsec_gss library supports setting debug level, increases the verbosity of the output (can be specified multiple times).

-R realm
    Kerberos tickets from this realm will be preferred when scanning available credentials cache files to be used to create a context. By default, the default realm, as configured in the Kerberos configuration file, is preferred.

-t timeout
    Timeout, in seconds, for kernel gss contexts. This option allows you to force new kernel contexts to be negotiated after timeout seconds, which allows changing Kerberos tickets and identities frequently. The default is no explicit timeout, which means the kernel context will live the lifetime of the Kerberos service ticket used in its creation.

SEE ALSO
rpc.svcgssd(8)

AUTHORS
Dug Song <dugsong@umich.edu>
Andy Adamson <andros@umich.edu>
Marius Aamodt Eriksen <marius@umich.edu>
J. Bruce Fields <bfields@umich.edu>