[Techtalk] question around port filtering, etc.

Michelle Murrain michelle at murrain.net
Thu Aug 23 08:46:36 EST 2001

Howdy folks,

I've got high-speed internet access through a cable modem provider. For a 
while, I was able to run a web server w/o any problem (using Dynamic DNS). 
It is against their rules, but...

Anyway, I had noticed they'd been portscanning me for a while (I was using 
snort). I didn't think much of it, until yesterday I found out that they 
are now filtering specific ports, including port 80, so people can't get at 
my web sites. (The wierd thing is that they have open and/or are filtering 
ports that I don't have open - i.e. the localhost nmap and external nmap do 
not match.). I have now decided to move to getting business DSL, because I 
really want the ability to host my own web sites, but that might take 
months. In the meantime, I've changed the port that httpd is listening to - 
and it's working, for now. I'm sure that they'll start filtering that port 
too at some point.

So this is my question: Is there any way to fool them about what port httpd 
is running on? There is nothing essential right now on the web site, but 
I've got a fair number of web programming projects that people are beta 
testing, or using for minor projects, and telling them what port to go to 
every other day is a pain, to say the least.  Also, I've got some mailman 
lists I was going to resurrect, but then folks wouldn't have access to the 
web interface easily. It would be nice if I could just set a port, and that 
port would work for the duration until I got new service.

Additional info - right now, the cable modem is plugged into a Netopia 
Router, which does NAT, and acts as a firewall. It can do some fairly 
sophisticated stuff.

Michelle Murrain
michelle at murrain.net

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