Greylisting is a way to filter spam and viruses based on the premise that these MTAs (mail transfer agents) do not act like real MTAs do (like Exchange, Postfix, Sendmail, etc.). Greylisting works by rejecting any unknown triad (IP address, Dest address, Source address) for 5 minutes, with the assumption that a valid MTA will then try to resend again in 5 minutes, but a virus or spam won’t.

Postgrey is a greylisting spam/virus filter for postfix that works almost 95% (spamassassin picks up the rest).

Although greylisting is not a new concept, I just implemented it and it is working better than expected.

If you have any experience with this or alternative methods like statistical analysis, post a comment below.

So after quite an ordeal starting at the launch of the Wii on 11/19, I finally have a Wii! I must say, after playing it for only an hour, I am completely addicted. It simply rocks.

Nintendo has done a great job putting together a gaming console everyone can enjoy.

Just stumbled across this elegant little fork bomb for Linux/Unix bash shells. Fork bombs perform a local DOS on a machine if the user is not limited to the number forks (usually set in /etc/security/limits.conf on Debian/Ubuntu systems).

From PacketFu blog:

. () { . | . & } ; .
0 1  2 3 4 5 6 7 8 9

0 - function name of our newly defined function
1 - parentheses declare a function with no (here optional) arguments
2 - block begins
3 - call self, the newly defined function (recursive)
4 - open a pipe to another process
5 - call self, the newly defined function (recursive)
6 - fork! (put the whole thing in the background)
7 - block ends
8 - end complex statement [ function declaration ]
9 - run that function!