SSH/Secure MUDding (was Re: Thoughts on PjD's Offline World Editor)

From: ShadowRealm MUD (
Date: 12/31/00

On Sun, 31 Dec 2000, Brandon Allen wrote:

> does anyone know how i would go about adding ssh to my mud?

Short answer, duplicate the built-in telnet server while hacking in SSH
source. It's certainly no small task, but the OpenSSH source is available
from and
mirrors or via ononymous CVS from and

> i want secure connections to my mud due to the face that we have MANNY
> local players hooked DIRECTLY to the network here that play from time
> to time. ( this is lanparty central ) the network is switched but i am
> still freaked ...

Justified paranoia indeed. Switched networking only keeps otherwise
uninvolved hosts out of the session sniffing action, but does nothing
against sniffing on potentially compromised servers, backbone routers or
other intermediary hosts. To take that paranoia a bit farther, many SSH1
implementations can be susceptible to MITM attacks as seen by the endless
fury of articles linked from slashdot in the past few weeks.

> i dont want to switch the whole mud over to ssh just maby add another
> socket to connect to / and or has anyone ever tryed to have more than
> one open socket to there mud as this is where i must start to even
> begin. and this socket is playable just like the 4000 ( stock socket)
> socket?

I would suggest against taking this route. Not only is there a daunting
quantity of code to patch in, but you will have athentication and
key-issuing to deal with (possibly store RSA or DSA public and private
keys in the mud passwd file?). Then there's the constant patching. New
patches to SSH/OpenSSH crop up monthly it seems. The constant bugfixes and
security patches would need to be integrated into your mud source tree
quite often.

> anyone have any ideas. and am i the first person to bring this up.

You are certainly not the only person to ask this. The archives should
show that I asked it probably 8 months ago before I investigated the
possibilities more thoroughly.

One suggestion that was hinted at by another reply was to set up an SSH
tunnel or proxy. I had something like that going for a while--a securmud
user on the server whose default shell was "telnet localhost 4000". It was
suggested that this was a problem for determining from what host a player
was MUDding. Not really an issue if you coordinate your MUDlogs with sshd
lines in the syslog. And players can be easily blocked with an
ipchains/ipf/ipfw rule on the appropriate host or via hosts.deny if you
compiled tcpwrappers support into sshd.

I personally don't like the idea of having a passwordless account on a
host on my network, so I abandoned this line of thought after a while. It
shouldn't be an issue if you take host security seriously, are careful
about how you compile and implemnent all involved apps and keep up on all
vendor patches religiously. I just felt it was a kludge and that there
must be a better way...

Enter IPSec. I now have IPSec VPN support activated on my NAT and being
tested. ShadowRealm is under development as a fetish MUD, and we'd like to
promise complete anonymity and security to our players. IPSec clients are
available for almost every desktop and server OS in use. Many are even
free (beer) open source apps (OpenBSD IPSec, Linux FreeSWAN, et cetera).
Seemed like the best option to me and required the least coding for the
best security. Just my tuppence.

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