NAME¶
rpc.gssd - rpcsec_gss daemon
SYNOPSIS¶
rpc.gssd [-D] [-f] [-n] [-k keytab] [-l] [-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¶
- -D
- DNS Reverse lookups are not used for determining the server
names pass to GSSAPI. This option will reverses that and forces the use of
DNS Reverse resolution of the server's IP address to retrieve the server
name to use in GSAPI authentication.
- -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.
- -l
- Tells rpc.gssd to limit session keys to Single DES
even if the kernel supports stronger encryption types. Service ticket
encryption is still governed by what the KDC believes the target server
supports. This way the client can access a server that has strong keys in
its keytab for ticket decryption but whose kernel only supports Single
DES.
- The alternative is to put only Single DES keys in the
server's keytab and limit encryption types for its principal to Single DES
on the KDC which will cause service tickets for this server to be
encrypted using only Single DES and (as a side-effect) contain only Single
DES session keys.
- This legacy behaviour is only required for older servers
(pre nfs-utils-1.2.4). If the server has a recent kernel, Kerberos
implementation and nfs-utils it will work just fine with stronger
encryption.
- Note: This option is only available with Kerberos
libraries that support setable encryption types.
- -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>