Changing your TCP/IP packets before they leave your PPP (Or external interface)...

[Planet X]

What is the syntax for manipulating my TCP/IP packets so that...

#1... My actual Eth MAC address is not used. (For now, I shouldnt worry
since
                 my external interface is a 56K modem/PPP)
#2... And my OS/Proxy version and details are not queried from some
hacker...
               Some hackers on ICQ get my IP and they cut-n-paste that I
have
                RH 7.1 beta (Roswell), Squid 2.4.1 stable and a couple of
other details.
                 I am not sure what they are doing to achieve this query!
Arrgh.
#3...  and in a worse case scenario, I would like to have my PPP interface
IP #
               actually reported as a differant IP # (spoofing) but spoofed
with an IP #
                  that is just 1 or 2 numbers higher. Or is this morally
wrong to do? ;-)

I know Netfilter well enough to know that its probably possible to do these
things
but how?

incidently, I get into trouble with my firewall because I basically have
everything opened
and I simply close little holes here and there. So, the hackers on IRC like
to play with
me. ;-) Its been great learning though! I need to start getting serious!

Thanks!

Joel