In article , Jonathan Goodchild wrote: :I need to find an Access Server suitable for the following application:
:A terminal dials in to the access server, which then establishes a TCP :connection to a host.
Your posting spurred me to remember a brand name for these kind of devices that I'd been trying to think of : Gandalf, from Gandalf Data Ltd. now apparently part of Mitel. Unfortunately the relevant products appear to have been discontinued, but you might be able to find some on the used market, If my recollection is correct, they were never "exciting" devices but they were real work-horses. It appears that Gandalf made at least one such box for interface with ISDN.
:The serial (i.e. asynchronous) data stream from the :terminal is then forwarded over the TCP connection, and the TCP data stream :from the host forwarded over the dial-up serial link to the terminal.
I have been (when I have spare time!) investigating devices that are similar, only used in reverse: "serial to ethernet convertors". My application is a need to drop an ethernet device somewhere and connect to it remotely so as to be able to talk to a remote serial port. I have found quite a number of such devices, with a *big* price spread. I have encountered models with 1, 2, 8, 16, and 32 ports, and models that were expandable in groups of 32 up to at least 228 if I recall correctly. I have also encountered Windows software designed to grant remote control over serial ports -- not useful for -my- purpose, as I don't want to drop a full computer out there, but possibly useful in your situation.
Some of the devices I have found allow ssh or ssl connections.
Probably the main difference compared to an "access server" would be in the authentication mechanisms available, and in matters such as detecting dead lines, or timeouts, and in ability to control modems via chat scripts; I would not expect advanced features from the lower end "convertors". Sometimes advanced features are not needed, though.