MUDitM

MUD in the Middle Telnet SSL Proxy

MUDitM is a telnet proxy that provides an IPv6 and telnet-ssl frontend to standard IPv4/telnet Multi-User Dungeon type games that have not implemented those networking features yet, whatever the reason. The implementation differs from other secure proxy implementations in that it tries to report the proxied client address up to the game server via the NEW-ENVIRON / MNES standard.

The latest version is MUDitM-0.2.tgz.

                        MUDitM - MUD in the Middle Proxy

       ******* This is the MUDitM-0.2 semi-secret alpha release! *******
                        Thu Mar 18 11:33:23 AM EDT 2021

MUDitM-0.1 is a telnet proxy that I wrote on a whim over a long weekend.  My
intent was to try to provide an IPv6 and telnet-ssl front end to standard
IPv4/telnet Multi-User Dungeon type games that have not implemented those
networking features yet, whatever the reason.  MUDitM-0.2 has another weekend's
worth of polish on it.

The implementation differs from other secure proxy implementations in that it
tries to report the proxied client address up to the game server via the
NEW-ENVIRON / MNES standard.  (See https://tintin.mudhalla.net/protocols/mnes/
for docs on MNES.)  I went for that method because my MUD already understands
it. 

This 0.2 release is more of a proof of concept than anything else.  It differs
from the 0.1 release in that it now uses PCRE2 as its back end pattern matching
engine, it allows configuration of multiple ip address reporting variables, and
I added the stunnel PROXY announcement as an option for games that already
support that.


Compilation, Installation
-------------------------

It'll compile and run on Ubuntu 20.10 and compatible systems.  You'll need to
install gcc, gnumake, libglib2.0-dev, ctags, pcre2 and openssl.

See INSTALL file for the barest of documentation.  There's no installer written
yet.

Installing it on Windows or Mac?  Le'me know how that goes.

What I've learned from this project:
------------------------------------

    1) At least for my mud, throwing an SSL socket into the game server really
    isn't as involved as I thought it might be, and it could even be worth
    doing in game for as long as we have support for "3rd party" mud clients.

    2) There is a another ssl proxy project out there called `stunnel`
    (https://www.stunnel.org/) that I had looked at briefly, but did not try
    out because I didn't realize that it had its own way of sending the remote
    networking address info through the proxy.  It does, it is very
    straightforward, and would be pretty trivial to add to a mud server that
    doesn't already do NEW-ENVIRON. So, I added that PROXY reporting method to
    MUDitM for the sake of compatibility.

    3) PCRE2 looks kind of daunting from the documentation.  Its not.

Bugs, Limitations, Todos
------------------------

MCCP2 and MCCP3 are de-negotiated by MUDitM, because it doesn't understand zlib
compression.  Maybe someday it will.

You've got to be careful with adding patterns via pcre2.  Don't include sub
match expressions, or you are going to screw up my 'what just matched'
algorithm.  (see also: "ret-2" buried somewhere in proxy.c.)

I did a crummy job of handling write(). They aren't queued properly at all for
partial or zero writes.  Oh well, maybe get that fixed for the beta release.

The IPADDRESS injection from MUDitM happens as soon as the server makes a
request for the full environment set.  If the client is also going to export
IPADDRESS, MUDitM does nothing to prevent that, and the client's export will
update the value seen on the game.  This is both good and bad- it is good,
because it lets a chain of proxies forward the first IPADDRESS along
unmolested.  It's bad in that it lets the client control the value of
IPADDRESS.  If you want to have access to the address that MUDitM is connected to
on the other side, export it using a different, less likely to be overwritten
variable name.  This is an area that could use improvement.

Contributing, Bug Reporting, Support
------------------------------------

You can contact the author (see the AUTHORS file) with your questions, bug
reports, or patches! The most up to date .tar.gz version of MUDitM can be found
at:

https://last-outpost.com/LO/pubcode

Now before you ask- there is no "sourceforge" or "github" or "gitlab" or
"slack" or "google code" or "public svn" or other "open source repository" for
this project.  Nope, I do not want help setting one up.  Thanks for the offer
though!

If you found this project on one of those repos, you can safely
assume that is a fork of MUDitM, and it has nothing to do with me, the original
author.  I probably won't be looking at it, so don't get mad when I don't
respond to things that have been posted to wherever that is.


Releases

PLAY NOW