Redirectors - moving modems from direct connection to a pool server
Neil Todd <toddn @
Thu, 25 Apr 1996 17:39:29 +0100 (BST)
Perot Systems Europe at Swiss Bank Corporation (London)
+44 1 71 711 3480 (voice), +44 1 71 711 3131 (fax)
I have the following problem:
A bunch of machines, running a variety of operating systems (PCs - Windows,
Windows 95, NT, Unix - Sun, ...) have modems connected directly to their
The systems are networked.
The systems run applications that I don't have the source to. Some of the
applications may have the name of the serial port device (e.g. COM1:)
I am being required to come up with a solution that will allow me to move
the modems into a set of central modem pool. I will need to keep some accounting
data about the usage of each line, so I may need to put a housekeeping
preamble in to pass 'user' information across to the server.
What I need for the PCs is to have a 'redirector' so that when an
applications opens COM1: say, instead of connecting to the local serial
port,the call is intercepted and rerouted over the network - using IP - to a
listening program on a Unix firewall server. The program will then do what
ever is necessary to connect to the modem. The service will need to be as
transparent as possible to the original PC application.
The Unix side of this I can probably handle myself, pseudo tty games come to
mind - but would be interested to know of other techniques that have been
found to work.
So, any thoughts or expertise on redirectors of this nature.
I appreciate that one technique won't work on every platform.
I have had suggestions about the use of the TAPI, anybody worked in this
Neil Todd | ..In general, it is best to assume that the
Perot Systems Europe | network is filled with malevolent entities
at Swiss Bank Corp (London) | that will send in packets designed to have
com | the worst possible effect... RFC 1122