Denial of Service

A common game played by people with far too much time on their hands is that of denial of service attacks. They almost entirely fall under the concept of spamming.

DoS Attacks

Fork Bomb

Problem: A simple attack where a process continuously creates copies of iteself. This eats up system processes and slows a machine to a halt

Solution: Most operating systems (not Linux) have a mechanism for limiting the number of processes a single user can have running at one time.

malloc bomb

Problem: Another simple attack which eats up system memory causing swapping to occur and machine slow down

Solution: Some OS's (not Linux) allow you to set a maximum memory limit per process.

SYN Flood

Problem:A marginally technical attack which leaves tcp connections in an uncompleted state. This uses up a lot of system resources and can slow a machine down to a crawl as well as cause connections to be dropped.

Solution: Increase the buffer size in your kernel for handling connections. Place a firewall (sacrifice) machine between you and the network.

Mail Bomb

Problem: Lots of mail messages fill up disk space, system processing power, and its just plain annoying.

Solution: Install a mail filter which will check for garbage mail and throw it into the bin of /dev/null It is also possible to have newer versions of sendmail filter out mail from specific hosts.