[TriLUG] Road Runner blocking ports?

[Keith Mitchell]

It would be interesting to put a picket sniffer (ethereal, etc.) in the 
middle and see whats actually going on.  I do know for a fact that RR 
did do some magic to prevent FTP servers from working over their cable 
modems in the past.  I had this problem about 5 years ago before 
switching over to the RR business cable modem.  I was actually using a 
GUI ftp client on windows when I detected this.  This particular FTP 
client showed you the connection stream (which in essence served as a 
sniffer).

Normally the FTP protocol will either issue a 'PORT' or a 'PASV' command 
to setup the data port (after logging in successfully).  But what I saw 
was this command was coming across the wire incorrectly... I forget 
exactly what it looked like, but they had changed one letter of these 
commands which was causing FTP to not be able to setup its data 
connection.  I moved my ftp server to a different port (something like 
10021... it was for my own use anyways and not public so I didn't care 
at the time) and it worked fine.

I don't know if they are still doing this or not, but that was my 
experience about 5 years ago,

Mark Freeze wrote:
> Whe I got home yesterday I turned on the 'Allow Passive Transfers' option in
> the config file, but, I'm still having the same problem.  I am not using a
> 'client' program to connect. Im just going to a command prompt on my $M box
> and doing ftp from the command line.
>
> This may be a problem with my d-link firewall-router.  When I enabled the
> virtual server ftp option on the d-link, it only opened port 21.  In fact,
> it showed 'Private Port 21 - Public Port 21'.   I another rule for 20 but no
> luck.
>
> I looked at the d-link help for their virtual server feature but it kept
> referring me to works by the noted Spanish author 'Manual'.  I may have to
> check out his stuff this evening.
>   


-- 
Keith Mitchell
Email: kmitch at guru.org			PGP key available upon request