rpc.gssd(8)rpc.gssd(8)NAME
rpc.gssd - rpcsec_gss daemon
SYNOPSIS
rpc.gssd [-f] [-n] [-D] [-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 particu‐
lar, 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 spe‐
cially, 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 implementa‐
tions, we now look for specific keytab entries. The search
order for keytabs to be used for "machine credentials" is now:
root/<hostname>@<REALM>
nfs/<hostname>@<REALM>
host/<hostname>@<REALM>
root/<anyname>@<REALM>
nfs/<anyname>@<REALM>
host/<anyname>@<REALM>
-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).
-D The server name passed to GSSAPI for authentication is normally
the name exactly as requested. e.g. for NFS it is the server
name in the "servername:/path" mount request. Only if this
servername appears to be an IP address or an unqualified name
(no dots) will a reverse DNS lookup will be performed to get the
canoncial server name.
If -D is present, a reverse DNS lookup will always be used, even
if the server name looks like a canonical name. So it is needed
if partially qualified, or non canonical names are regularly
used.
Using -D can introduce a security vulnerability, so it is recom‐
mended that -D not be used, and that canonical names always be
used when requesting services.
-R realm
Kerberos tickets from this realm will be preferred when scanning
available credentials cache files to be used to create a con‐
text. By default, the default realm, as configured in the Ker‐
beros 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 ALSOrpc.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>
14 Mar 2007 rpc.gssd(8)
