TSBRIDGE(8C)

NAME
tsbridge - Transport Service Bridge

SYNOPSIS
tsbridge [-a address] [-s] [-T tailorfile] [configuration-file ...]
(under /etc/rc.local)

DESCRIPTION
The tsbridge listens for transport connections on the given address. Once a connection is accepted the transport selector is examined for a transport address and a call initiated to that address. The TSB then shuffles data back and forth between the two connections. This is used to solve interworking problems between OSI hosts/networks using different lower-layer stacks (e.g., TP0/X.25, TP4/CLNP, RFC1006/TCP, and so on).

Entries are separated by end-of-line (or the end-of-file). The character `#' at the beginning of a line indicates a comment line. The syntax is:

address [forwarding-address] [-s] [-n] [-f]

as in

# generic tsb operation
Internet=sheriff+19001\|Janet=000021000018+PID+04010100
# specific use of transparent address with strict checking
Internet=sheriff+19002 Internet=sheriff+102 -s

If the forwarding address is present, this specifies that the tsbridge should run in transparent mode. That is, it should accept incoming connections as though it were the tsapd daemon and a call established to the given address (which is normally a tsapd process or a static listener).

The `-s' option specifies strict transport addresses. When relaying through the tsbridge the calling transport address is changed to indicate that of the tsbridge. This can fail in several ways:

1.  The original calling address when encoded into a string may be too big to fit into the transport selector.

2.  The tsbridge may not be listening on an address on the outgoing network. (E.g., it can call out on that network but not accept incoming calls.)

3.  The original calling address can not be converted to a text string (unusual).

In strict mode, any of these failures will abort the connection attempt. If strict mode is not in force, then the bridge will leave the original transport address alone and hope it is not needed.

The `-n' option specifies that the original transport selector should not be changed to indicate that the address came from a transport bridge. This effectively passes the original T-Selector through unchaged. This option is implied if a forwarding address is present.

The `-f' option overrides the default application of the `-n' flag when a forwarding address is present. This permits one to set up a semi-transparent listener --- transparent to the caller, visible locally.

If desired, the tsbridge can run without a configuration file, in which case the `-a' flag specifies the address to listen on. If this is not present, it will use use the value of the “tsb_default_address” variable in the tailor file for the default address. The `-s' flag may also be specified in this case.

Finally the `-T' flag specifies a different isotailor file to use. This should be a full pathname and, if present, should be the first argument given.

EXAMPLE
A configuration file on host 128.199.200.7 has in its tsbridge configuration the line

# specific use of transparent address with external visibility
Int-X25(80)=234212900115+PID+03010100 stcTCP=128.199.200.43+102 -f

A call placed to 234212900115+PID+0301010 from X121+23421920030045 will appear at the final recipient [128.199.200.43] to come from

"X121+23421920030045"/stcTCP=128.199.200.7

FILES
isotailor	ISODE tailoring file

SEE ALSO
The ISO Development Environment: User's Manual, Volume 2: Underyling Services, “The Transport Switch”.
isotailor(5), tsapd(8)

AUTHORS
Julian Onions, Nottingham University.
Based on an idea by Steve Kille of University College London and Christian Huitema of INRIA.