Re: IPFWADM and telnet
> > At 00:41 22-11-96 -0500, Adam Heath wrote:
> > |I current connect to the Internet with PPPD, and all works well. I
have
> > |compiled my kernel (2.0.24) with IP_MASQ enabled, and have verified
that
> > |this works. Here is my question.
> > |
> > |Can it be setup, so that when someone telnets into the Linux box,
> instead
> > |of the request being handled there, it is masqueraded to one of the
> private
> > |computers on the LAN? I have a DOS-based BBS that I can setup to
accept
> > |incoming telnet, but it won't work through DOSEMU.
> > |
> >
> > It's possible. Have a look around for the 'redir' package, which will
do
> it
> > for you.
> >
> Not what I want. I have looked at 'redir'. I would like it to be
> implemented more at the kernel level. Currently, I can run this command:
>
> ipfwadm -I -P tcp -a accept -S 0/0 -D 127.0.0.1/32 23 -r 1000
>
> That will take packet coming from anywhere, headed toward the local
telnet
> port, and redirect it toward the local 1000 port. Why can't I also put
in
> a destination system address? I currently setup 'redir' to listen on
port
> 1000, and redirect it across the LAN(actually, across a simulated SLIP
link
> between linux and DOSEMU), but it seems I should be able to do something
> like it with the kernel.
>
> If I need to talk to the kernel guys, then if someone could direct me to
> the proper mailing list, I will post my question there. Txs.
>
To those who are interested. I have finally got this to work.
I hacked the 'redir' source to cycle back and forth between to ip
addresses that are hard-coded into the source as each connection
comes in. Then I setup a simulated SLIP connection bewteen linux
and two dosemu sessions(read the "Stacker" mini howto). In each
dos session, I used 'rlfossil' to translate between the fossil and
telnet specs, and ran a dos-based bbs.
I then telnetted to my system on port 1000(where 'redir' was set
to listen). I got a connect on line 1 from the bbs. I aborted the
connect. I then immediately telnetted again to port 1000. This
time, it connected on line 2! I about sh*t myself when I saw it!
Now I just need to get it to load automatically. I have a script
created to run the programs on the linux side. I just need to
make a script that can load the dos sessions automatically.
If you think this is a lot to do on one machine, but the way I hacked
the 'redir' program, it will work with many machines on a private
lan. As each telnet connection comes in to the linux machine, it
can be redirected to any number of IP address. If the kernel has
a route to the address, then it will work. So I could have the 2
bbs channels residing on another computer on the private lan, 1
channel residing in DOSEMU on linux, and even another channel
residing on a distant machine on the Internet!
I am planning on making a HOWTO out of this, also, to make
it easier for others to implement this.
(I wonder if it would work with other protocols [FTP, HTTP, whatever])
Adam Heath
doogie@shianet.org
http://www.geocities.com/Siliconvalley/Park/6562/
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