Stupid Question - Proxy Internals

[Josh Frick]

I've just added a Dante/Squid proxy to my network,  and I'd like to know 
if this is significantly more secure than packet filtering.  I can't 
seem to get a straight answer from online documentation for Socks,  and 
I know Squid is not inherently secure,  but I have a fairly 
straight-forward question:
   Do Socks4/5 and/or Squid actually prevent packets with inappropriate 
protocols from being passed on to the client (i.e. telnet to port 80)?
   If not,  what does?

  Sincerely,
  Josh Frick