Subj : VMODEM
To   : Tommi Koivula
From : Torsten Bamberg
Date : Fri Aug 23 2019 09:19 pm

Hallo Tommi!

21.08.2019 20:01, Tommi Koivula schrieb an Torsten Bamberg:

>> Currently my vmodem and telnet ports are down, but usually I have 8
>> telnet ports running, with one instance of vmodem(2k).
TK> 8 different TCP ports?
I meant telnet-sessions simultanously. Of course only port 23 is attached.

TK> My Vmodem of SIO 1.60 has 16 "ports", but listening only one TCP port.
I'm using sio2k. sio2k supports 256 'sessions', witch can be telnet, com-ports
or com emulated capi-devices. I've got one big problem with sio2k, I can't
register it any more.

TK> Which is 23 BTW. And that port is not exposed to the internet, my
TK> router forwards external port 32 to port 23 at OS/2 computer.
Ahm, i've got a special security configuration, not only because of the
'unclosed session bug' from sio2k


 cable -->-- cable-router -->-- Router 1         Firewall 1
   dsl -->--  dsl-modem   -->-- BSD-Router -->-- BSDFirewall
                                                  |   |   |--->--- DMZ
                                                  |   |
                                                  |   |--->--- LAN
                                                  |
                                              -> Firewall 2
                                              |  with fail2ban BSD
                                                  |
                            RexxLogScripting  ^   |
                                              |  Telnet on
                                              -- Mailbox 01

Security by obscurity. ;-)

>> But there is one big bug with vmodem; if the clientsession isn't
>> closed properly, vmodem hangs up the whole computer without a trap.
TK> Oh?
Jap. If more than 256 connections are opend, and not properly closed, sio2k
does hang up the system.

TK> 'Tommi
Bye/2 Torsten

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