A software firewall can't keep programs that are running on the same machine, as the firewall, from accessing the internet. There are many ways to tunnel a firewall. As long as the program runs on the same machine nothing keeps it from giving itself a rule to allow traffic or just use your standard browser to communicate.
Ironically ZoneAlarm was one such program that tunnels the firewall (in this case, itself).

FGR, I'd use the Windows Firewall, if you need one. It does everything a firewall can do, without messing up your internet connection.

Configure your software correctly and use only software you trust.

Just for purposes of clarification, you are saying that there's nothing to prevent the firewall, or programs that disguise themselves as the firewall software, from accessing the network and the Internet?

I would agree then that, yes, if a program can somehow fool a software firewall into thinking that the program is the software firewall, then that layer of protection fails. But that doesn't strike me as a sufficient reason to simply disregard it as a useable protection tool, as I'm not under the impression that there are any large number of cases of malware or viruses/Trojans that do this (in fact, I'm not sure there any at all).

Once malware is run you've lost anyway.

My point is, most personal firewalls claim they can do something, which is impossible for them. If what you want is "I want to be able to keep every program from the internet, at least if it's friendly enough to let itself be controlled." Then go ahead and use a personal firewall.
I run a program, because it has a purpose. Every program you run poses a security risk. Every software has faults. That's why I only run programs I need. I don't need a personal firewall to controll my programs, I controll them through the means they give me. And if a program does something I don't want I don't use it.

There are a great deal of viruses/trojans that disable firewall software, including zonealarm and window's own firewall.

And there are a great many viruses that target anti-virus software, so it must be better to just not use it, right?

Impi - to say that once malware runs, you've "lost" is a fair bit dramatic. Spyware and adware are types of malware that can often be easily removed, and a software firewall helps to ensure that, until these pieces of software are found and removed, their function is inhibited.

Anti-Virus programs can detect said viruses and trojans before they do damage. Firewalls can't.

(Thus, why you use anti-virus in concert with a software firewall)

Actually, the better software firewalls have anti-tampering stuff. Protected memory and all that. We need anti-virus and firewall written in C# or Java.

But the software firewall doesn't ensure anything.
Perhaps you know that it has blocked some attempts of communication, but you can't be sure that it's blocked all attempts.
And you can't be sure that the removal instructions got everything. Perhaps they got the apparent adware stuff but left behind the backdoor that only activates every second thursday in order to hide from adaware and co.

I may be a little paranoid, but that doesn't mean that every malware programmer is an idiot.

(To be picky, I said "helps to ensure", not "ensures")

I should note that I've never said that, with a personal firewall, you're guaranteed to be safe from all threats. It's a combination of anti-virus, firewall (preferably hardware + software, though hardware > software), good practices, anti-malware software, and keeping up with patches to software.

No single thing is going to make you 100% safe. No culmination of layers of protection will make you 100% safe. But a software firewall, in my experience, reduces the likelihood of problems due to the hackers, Trojans, spyware, adware, etc.

Also, you describe yourself as paranoid, but your apparent substitute for a personal firewall is "The programs I use only do the stuff I want them to", which seems somewhat silly, since you can't be 100% sure that you won't screw up somewhere along the line and accidentally end up with a Trojan piggy-backing on a program's installer.

QBIT

Quote Butter Insult Truffle?

Quoted because it's true

I like mine better.


This discussion should now shift to why having so many dumb acronyms is hurting the english language.