How save is my cs set

[sky pirate]

I have a small card share set, for now i only share it with 1 friend.
F: user pass (as simple as that)
C: server dyndns.info 12000 user pass (as simple as that)

Now, how save is this. Everything in the set is on standart settings,
Dreambox and router, everything.

Not only if somebody can watch threw my card, whats about my
Computer, is this a big open door now?

Which things should be made save (make a password)

Somebody will give me or us a little lesson in “make your set save”
thnx

[nobby11]

just password protect your router