For perspective: You should consider that once you connect your computer to the Internet, the entire Internet (and every user on it) connects to your computer.
If you are considering a Broad Band connection (ISDN/DSL/Cable/Satellite) to the Internet from your home, then security of that connection and your computers should be a concern. There are different parts of your security needs and different solutions for your needs available depending on your funding, and time.
The first part of security for you to consider is controlling connections
TO your computer. Depending on your operating system
someone from the Internet may be able to connect to your computer
and damage your system or compromise your data. Most often people
accomplish protection of this sort with a firewall. Each
computer has 65536 "ports" for different programs and services to
use, www (or http), for example, operates on port 80. A firewall
serves to block all the ports to your computer only allowing the
ports you have specified to be available. There are many different
solutions available ranging in price and features.
The second part of security for you to consider is controlling
connections FROM your computer. If you telnet from
your home into a University computer, then any information that
you send across that connection will be in plain text and anybody
along your connection can "sniff" your data and see everything that
you see in your telnet session. This "sniffing" can pick up your
username, password, grades, etc. Anything that you send over your
connection that is not sent to a secure server can be read.
One immediately available solution is to never use telnet. OpenSSH
will allow you to open a secure connection using SSH - it looks
and feels like telnet, but is secure. More Information on
is available here.
Depending on the level of access and what resources you need access
to you should discuss Virtual Private Network (VPN) with your support
personnel. One possible way to implement this is through the use
of Point-to-Point Tunneling Protocol (PPTP), but since Username
and Password are transmitted in plain text before the PPTP session
is started a separate username and password should be used, and
once connected you should be required to authenticate for any additional
resources you use over the connection.