• inbound telnet

    From John Kelly@2:362/6 to All on Sat Dec 6 22:18:00 2014
    As most people already know, there is netfoss for inbound telnet. I once
    tried it, but it had no protection against port probes. All you could do
    was add IP addresses to the filter list. But by then, it's too late, the
    port probe already has a different IP address. Playing whack a mole with
    port probes is not for me.

    So I looked into the telnet protcol to see if I could filter out port
    probes automatically. I found a method that's simple, but not foolproof.
    The probes could defeat it, if they were smart. But after more than a
    year of testing, I've never seen a probe defeat it. They repeat the same failing tricks over and over.

    I also wanted to run PCBoard the traditional way, sitting at the call
    waiting screen while idle. You can't do that with netfoss. So I wrote a
    reverse telnet proxy. It runs on a linux box to take inbound telnet
    calls, and you connect back end PCBoard nodes to the proxy, and they
    handle the calls. The back end connection is via null modem serial
    cable, assuming you have a multiport serial card on your linux box, or
    a tcp network connection over your LAN.

    For the tcp connection, you need a tcp fossil driver for PCBoard. So I
    wrote one; it only works with the tcp/ip stack from Novell Client32 for DOS/Windows. That means it only works with PCBoard nodes running on DOS
    or Windows 3.1. My test setup easily runs two nodes on Windows 3.1, I
    think it could handle up to four nodes.

    The name of my proxy is btbbx. I uploaded an early version to Luis BBS,
    but that was almost two years ago. Since then, I've made countless fixes
    and improvements. I've hammered it hard to shake out the bugs, it's good
    enough to use. I've not uploaded the new version, but if anyone wants to
    use it, say so, and I'll see about uploading it.

    --- PCBoard (R) v15.4/M 250 Beta
    * Origin: Torres Vedras - Portugal (2:362/6)