I'm actually quite surprised at the "accuracy" of the matrix and hacking abilites in SR4. It almost seems like they asked a programmer to help describe the rules. I'm a software engineer and in my free time occasional hack the planet and write the internet. Like the way they explain things - that you're not actually breaking a firewall as if it were a mob, you're just looking for a hole which can later be patched up. Thats how its done nowadays.
The kind of exploits they talk about a lot are referred to commonly today as "zero day" exploits. A zero day exploit is an issue that a hacker discovers but no one knows about it i.e. the company that makes the software, anti-virus and security companies like norton, Microsoft. There are people who hoard these "zero day" exploits and they are referred to as "dragons". They mostly live across the seas where software criminal laws are leanient to non-existent. These people make their living doing jobs for people or selling security flaws to others, in fact this is how companies like Norton find a lot of the holes their software plugs - they pay for it. There was recently someone caught, can't remember for what, think the police got him on a forum but he had something to the tune of 13 zero day exploits which is unheard of as most people who are good at what they do usually run into two or three in their lives.
The way the books talk about source code and programs is all surprisingly accurate as well. I really like the way they handle hacking in/editing systems especially the extended tests. The longer you run a program against something like say a brute force program, the closer it gets to the answer - it just takes time.
If you guys want to play around hacking the crap out of things download cain & abel
http://www.oxid.it/cain.html. The newer version includes packet sniffing,packet injection, arp poisoning, password recovery, and wireless SSID cracking (provided you have the right adapter). There are also some other neat tools like nmap/zenmap
http://nmap.org/zenmap/ which is a network security analzying tool. Nmap is the same kind of tool a hacker in the SR4 univers would use when looking for weaknesses in a system. There's lots of other fun ones but yeah! I love the flavor in SR4's tech :3
DizDiz!