What are the firewalls present on a normal installation of hardy?

[Steven Vollom]

I am only getting about 70kbs of download speed.  AT&T says I should be 
getting between 384 and 768 kbs.  They say that a router slows the speed.  Of 
course they don't service Linux, but what do you suggest I say to them.  I 
haven't installed any firewall that I know of, other than any that were 
automatically installed with the OS.

Steven