pmsocks (1)

pmsocks path [args ...]

pmsocks allows Performance Co-Pilot (PCP) clients running on hosts located on the internal side of a TCP/IP firewall to monitor remote hosts on the other side of the firewall. This assumes the firewall has been configured with a compliant sockd daemon and the necessary access controls are satisfied.

pmsocks uses the tsocks(5) library, which is not included with PCP. You can get tsocks from http://www.progsoc.uts.edu.au/~delius/.

On IRIX, pmsocks is simply a shell wrapper that sets the appropriate environment variables and then executes the path program with args arguments (if any). pmsocks works by setting the _RLD_LIST environment variable (see rld(1)) to load a dynamic shared library (see dso(5)) containing stubs for ``socksified'' network library functions; This ``socksified'' library is installed at /usr/pcp/lib/libpcp_socks.so.

There are a number of conditions required for this to be successful and the user is strongly advised to read this whole manual page (in particular the CAVEAT section below) before attempting to use pmsocks.

When pmsocks is installed, the /etc/pcp_socks.conf configuration file is also installed with minimum default settings. These settings specify that socket connections to the local host should be made directly, without contacting any socks server daemon. This is necessary so that PCP clients will be able to establish a local connection to the X(1) server, and use PCP connections, possibly via a sockd daemon, to monitor remote hosts. In the present implementation of pmsocks, non-direct connections to the X(1) server do not work, hence if the display is remote, then the remote host must be on the same side of the firewall and /etc/pcp_socks.conf must be configured to connect directly to that host.

The format of /etc/pcp_socks.conf is identical to /etc/socks.conf as documented in the CSTC-4.2 socks distribution. This distribution may be obtained via information contained in the socks FAQ at ftp://coast.cs.purdue.edu/pub/tools/unix/socks/

If other socks clients are being used, then it is generally safe to remove /etc/pcp_socks.conf and instead make a symbolic link to /etc/socks.conf. The file formats are identical.

The default configuration should be customized to suit the local environment so that connections to hosts located on the same side of the firewall as the local host do not use the socks daemon unnecessarily. The default configuration is

direct LOCALHOSTNAME 255.255.255.255 # direct localhost

sockd 0.0.0.0 0.0.0.0 # contact sockd everywhere else

Note that the string LOCALHOSTNAME is dynamically substituted at run time with the name of the local host, as obtained by a call to gethostname(2). Assuming the real IP address of the local host is 1.2.3.4 and that a normal class-c subnet is used locally, the most common customization would be to specify direct connections for all hosts on the local subnet, by inserting another ``direct'' line as follows:

direct LOCALHOSTNAME 255.255.255.255 # direct localhost

direct 1.2.3.0 255.255.255.0 # direct on local subnet

sockd 0.0.0.0 0.0.0.0 # contact sockd everywhere else

The order of lines is important - the first line matching the requested destination IP address during a connect(2) call (after the requested IP address has been masked by the third parameter of the /etc/pcp_socks.conf line), specifies via the first parameter whether to contact the socks daemon or whether to attempt a direct connection.

There are several environment variables used by pmsocks as follows:

SOCKS_SERVER

Specifies the host name or IP address of the host running the sockd daemon. Usually this is the name of the firewall host.

SOCKS_PORT

The TCP/IP port to use when contacting sockd on the SOCKS_SERVER host. The default is 1080.

SOCKS_NS

The host name of the name server to use, usually to resolve the IP address of SOCKS_SERVER.

SOCKS_DEBUG

If present in the environment, libpcp_socks will print debugging information to the stderr stream. There are only two levels of debugging, on or off. This is only really useful for the developers because the debugging information assumes knowledge of the libpcp_socks source code.

SOCKS_BANNER

If this is set, whenever a client calls libpcp_socks it will echo a message to stdout containing version information. This can be useful to check libpcp_socks is working in the absence of verbose logging.

_RLD_LIST

pmsocks sets this to exactly /usr/pcp/lib/libpcp_socks.so:DEFAULT

It is strongly recommended this NOT be set in the environment of interactive shells.

PMCD_CONNECT_TIMEOUT

Specifies the time-out, in seconds, for connections to pmcd(1). When using pmsocks, this may need to be increased from the default (5 seconds) due to the additional delays introduced as a result of using sockd. See PMAPI(3) for further details about this variable.

The following notes should be considered carefully:

0)

Because sockd can only handle TCP/IP sockets, pmsocks never attempts to use sockd for sockets of type SOCK_DGRAM or if the domain parameter in a call to socket(2) is PF_UNIX (unix domain sockets should never need to use sockd anyway).

1)

Some firewall products do not support ``socksified'' applications, and in these cases, pmsocks cannot be used. In this case, it will be necessary to configure the firewall to allow connections through the firewall for the PMCD communications port, typically tcp/4321.

2)

The PCP protocol is TPC/IP-based and works with the socks protocol, but connections which use UDP/DATAGRAM sockets or remote X11 connections via sockd may not work. If the remote display host is on the same side of the firewall as the application, this may be circumvented by configuring the remote display host to use direct connections - see above. Also, using X11 display options which use shared memory may hang the X server when used with pmsocks.

3)

If the pmsocks configuration file is not present, then pmsocks will exit with an error message.

4)

pmsocks uses the locally configured name server or resolver (see resolver(5)) to resolve host names to IP addresses. This may or may not be capable of resolving host names on the other side of the firewall.

5)

When used over a WAN, often the sockd daemon will be a long way from the application. This may result in PCP client connections timing out before connecting to the remote pmcd. If this is occurring, set the environment variable PMCD_CONNECT_TIMEOUT to a higher value than the default (5 seconds). Refer to PMAPI(3) for further details about this variable.

6)

When using pmsocks to connect to pmcd(1), but ``Connection Refused'' error messages are returned, it is not immediately obvious whether pmcd(1) is returning the error or sockd.

tsocks is covered by the GPL license and is copyright Shaun Clowes ([email protected]).

/etc/tsocks.conf

configuration file

pmcd(1), pminfo(1), pmlogger(1), pmval(1), X(1), PMAPI(3), resolver(5), and tsocks(5).