sfssd_config5

Overview

sfssd_config configures sfssd, the server that accepts connections for sfsrwsd and sfsauthd. sfssd_config can be used to run multiple ``virtual servers'', or to run several versions of the server software for compatibility with old clients.

Directives are:

BindAddr ip-addr [port]

Explicitly specifies the IP address and port on which sfssd should listen for TCP connections. To listen on INADDR_ANY, use the value 0.0.0.0 for ip-addr. If port is not specified, sfssd will use the value of the SFS_PORT environment variable, if it exists and is non-zero, or else fall back to the default port number of 4.

It is important to note the difference between specifying a port number with the SFS_PORT environment variable, and with a BindAddr directive. See the description of the SFS_PORT environment variable in the sfs_environ man page for more information.

When no BindAddr directive is specified, sfssd attempts to figure out the appropriate port number(s) to bind to automatically. It does so by looking for DNS SRV records for the current hostname (or SFS_HOSTNAME environment variable). This is quite different from specifying BindAddr 0.0.0.0 0, which would always bind port 4 or whatever is specified with the SFS_PORT environment variable.

RevocationDir path

Specifies the directory in which sfssd should search for revocation/redirection certificates when clients connect to unknown (potentially revoked) self-certifying pathnames. The default value is /var/sfs/srvrevoke. Use the command sfskey revokegen to generate revocation certificates.

HashCost bits

Specifies that clients must pay for connections by burning CPU time. This can help reduce the effectiveness of denial-of-service attacks. The default value is 0. The maximum value is 22.

Server {* | @Location[,HostID]}

Specifies a section of the file that applies connection requests for the self-certifying pathname @Location,HostID. If ,HostID is omitted, then the following lines apply to any connection that does not match an explicit HostID in another Server. The argument * applies to all clients who do not have a better match for either Location or HostID.

Release {* | sfs-version}

Begins a section of the file that applies to clients running SFS release sfs-version or older. * signifies arbitrarily large SFS release numbers. The Release directive does not do anything on its own, but applies to all subsequent Service directives until the next Release or Server directive.

Extensions ext1 [ext2 ...]

Specifies that subsequent Service directives apply only to clients that supply all of the listed extension strings (ext1, ...). Extensions applies until the next Extensions, Release or Server directive

Service srvno daemon [arg ...]

Specifies the daemon that should handle clients seeking service number srvno. SFS defines the following values of srvno:

1. File server 2. Authentication server 3. Remote execution 4. SFS/HTTP (not yet released)

Service srvno -u path

Operates as the above syntax of Service, only instead of spawning a daemon, connects to the unix-domain socket specified by path to communicate with an already running daemon. This option may be useful when debugging SFS servers, as the server for a particular service on a particular self-certifying pathname can be run under the debugger and receive connections on the usual SFS port without interfering with other servers on the same machine.

Service srvno -t host [port]

Specifies that sfssd should act as a ``TCP proxy'' for this particular service, relaying any incoming connections to TCP port port on host. If unspecified, port is the default SFS TCP port 4.

This syntax is useful in a NATted environment. For instance, suppose you have two SFS servers with addresses 10.0.0.2 and 10.0.0.3 on a private network, and one machine 10.0.0.1 with an externally visible interface 4.3.2.1. You can use this proxy syntax to export the internal file systems. The easiest way is to pick two DNS names for the new servers, but point them at your outside server. For example:

  server-a.mydomain.com.  IN A    4.3.2.1
  server-b.mydomain.com.  IN A    4.3.2.1

Then, on your outside machine, you might have the following sfssd_config file:

  Server server-a.mydomain.com
    Release *
        Service 1 -t 10.0.0.2
        Service 2 -t 10.0.0.2
        Service 3 -t 10.0.0.2
  Server server-b.mydomain.com
    Release *
        Service 1 -t 10.0.0.3
        Service 2 -t 10.0.0.3
        Service 3 -t 10.0.0.3

Then on each of the internal machines, be sure to specify Hostname server-A.mydomain.com and Hostname server-B.mydomain.com in sfsrwsd_config.

The default contents of sfssd_config is:

  Server *
    Release *
        Service 1 sfsrwsd
        Service 2 sfsauthd
        Service 3 rexd

To disable the file server, you can copy this file to /etc/sfs/sfssd_config and comment out the line Service 1 sfsrwsd. To disable the remote login server, comment out the line for rexd.

To run an SFS read-only service, you could specify the lines:

  Server *
    Release *
      Service 1 sfsrosd

Note that you may have only one program per service number within a Release clause. For instance, you cannot run both sfsrosd and sfsrwsd unless the programs appear in separate clauses such as:

  Server *
    Release *
        Service 1 sfsrwsd
        Service 2 sfsauthd
        Service 3 rexd

  Server @snafu.lcs.mit.edu,xzfeqjnareyn2dhqxccd7wrk5m847rh2
    Release *
      Service 1 sfsrosd

To run a different server for sfs-0.6 and older clients, you could add the lines:

    Release 0.6
      Service 1 /usr/local/lib/sfs-0.6/sfsrwsd

Files

/etc/sfs/sfssd_config

/usr/local/share/sfs/sfssd_config

meta-server configuration

(Files in /etc/sfs supersede default versions in /usr/local/share/sfs.)