Dumb question about ports/packages

[Matt Rechkemmer]

This is somewhat of a dumb question, but I'm a bit confused about the
differences between ports, packages and what is currently on the system.
Let's [hypothetically] say I have a FreeBSD 5.3 system.  I use the ports
system on things I want to compile and packages when I'm lazy :-).

I keep track of my ports 'n' packages with portupgrade(1).  Now here's the
scenario (fake, mind you).  Let's say SSHD which is part of the core
distribution from my limited understanding develops a root hole, or some other
nasty exploit.

How would I upgrade just one package part of the core like that? Or multiple
ones for that matter.  Can you use the ports/packages system? Or do you have
to do an entire system upgrade (i.e. 4.10 to 4.11).  

Any help is greatly appreciated!

Matt Rechkemmer
tiberius at trancell.org