Re: IP Masquerading

Jos Vos (jos@xos.nl)
Tue, 4 Jun 1996 09:54:04 +0200 (MET DST)


> When I FTP now I recieve a
> ftp> dir
> 200 PORT command successful.
> 425 Can't build data connection: Host is unreachable.
> ftp>

Did you do "make modules" and load the "ip_masq_ftp.o" module? This
modules is needed to be able to use the reverse FTP data connection.

> I have masquerading partially working. It works with TCP but it seems
> that UDP services are not.. It *WAS* working for me with an earlier
> kernel. I did not do extensive testing, however. Actually, come to
> think of it, it may not have been working before earlier. I was using
> Netscape to FTP which I think uses TCP. I dunno. [...]

Netscape uses FTP in passive mode, so in that case you don't need the
ip_masq_ftp.o module. That might explain why it worked in the past.
If Netscape still works, loading the module will be the solution.

> [...] If someone could
> point me to a FAQ I'd be much appreciated. As of right now, I don't know
> if masquerading even supports UDP yet or I just have set it up wrong.
> (I did it via trial-and-error)

Yes, masquerading does support UDP more-or-less. When a UDP packet is
sent out, it recognizes "answers" to this packet the next two minutes.
Because UDP is stateless, this isn't a perfect solution (which is in
fact theoretically impossible), but it will work in most cases.

-- 
--    Jos Vos <jos@xos.nl>
--    X/OS Experts in Open Systems BV   |   Phone: +31 20 6938364
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