IP Masq and FTP

by Chris Tyle » Fri, 09 Jan 1998 04:00:00

I've recently installed an old 386 as an IP Masq machine on my
home-office LAN. It's working very well (especially considering the age
of the hardware!) but I'm having varied success with FTP (using the
required module). It seems that I can reliably connect to all sites on
the command channel, I can't use the data channel on some particular
sites (it's reliably the same sites). I noticed that this is mentioned
in the IP-Masq HOWTO but I can't find any information about *why* this
happens, and if a workaround is available. Can anyone enlighten me?

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1. IP Chains / IP Masq FTP Problem

I've used IP masquerading via ipfwadm for about two years now with
great success. I just set up a new gateway for a cable modem, and I
decided to try IP Chains instead. I downloaded the source and the
2.0.34 patch, and I applied it to my 2.0.36 kernel. I spent some time
creating a firewall script, and everything seemed to work great! Or
so I thought.

I tried to use ftp - I would log on to a remote host, and as soon as I
tried a command like ls or get, I would lose my connection. I then
realized that I forgot to load the ip_masq_ftp module. I loaded it
and everything seemed to work great again... or so I thought.

I tried to use LiveUpdate for Norton Utilities and Norton Antivirus on
my Win95 machines. I would connect to the Symantec ftp site, but
would then lose the connection through the LiveUpdate software. I
tried to connect to the ftp site manually, but when I would try the ls
or get commands, I would lose my connection (just as I wrote above).

I re-installed ipfwadm (a new kernel), and the problem went away. I
like IP Chains because it seems more flexible, but I need to be able
to update my Norton Utilities and my virus definistions.

I tried compiling different kernels with the IP Chains patch, but I
couldn't solve the aforementioned problem. I've even loaded every
ip_masq* module, but I cannot correct this problem.

Does anyone know what's going on, and how I can fix it? I've tried to
find other IP Masquerading tools, but everything that I see mentions
ipfwadm.

Thanks!

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