Preventing local users from "text flooding" a terminal (DoS attack)...
Hi. I am having a problem. A friend and I keep going back and forth in our college Linux class, seeing which one can own the local server/network. There are approximately 20 users on the Red Hat 7.1 system, none of which have root privileges.
My friend recently took back the server my from grips by creating a process to TEXT FLOOD my terminal anytime I log onto the system. I cannot figure out a way to circumvent this problem and block the incoming DoS attack. CTRL-C/X doesn't do anything and the text keeps on flooding. As we do not reveal each others secrets, I assume that he has written a script to output the contents of a file continuously....something like "cat flood.txt | write user_name", which takes advantage of the fact that the WRITE command is allowed. Is there anyway to block this sort of activity?
When I secretly logged on as another user in the class (to avoid flooding), I exploited the KMOD/PTRACE vulnerability to get root on the local system and swiftly kill -9'd all his processes to regain control. The problem is that even if I have root privileges, his script still sees my user name logged on and continuously floods me... Your help would be greatly appreciated ;-)