Messages in this thread | | | Date | Tue, 9 Mar 1999 11:17:15 +0100 (CET) | From | Mikulas Patocka <> | Subject | Re: Simple DoS...out of resources? |
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> On Mon, 8 Mar 1999, Myrdraal wrote: > > > On Mon, Mar 08, 1999 at 01:39:24PM -0500, rewt wrote: > > Hi, > > > It is very easy to crash a system simply by viewing a large file with > > > editor such as pico. It will eat up all the resources and do some > > > unpredictible things. In my case I viewed a 100mb file as it was reading > > > it, it filled up all the swap space which is 48mb. It killed most of the > > > processes including sendmail, sshd, X, syslog. Does anyone have any idea > > > how can i protect myself against that kind of DoS? My configuration: > > > P100, 48mb ram, 48mb swap running on kernel 2.2.2. > > You need to set user resource limits. This isn't a kernel problem. See > > the "ulimit" command if you use bash. Other shells probably use a different > > command. > As a side note, the new versions of the linux shadow suite > support the /etc/limits command to force limits on users, and I > believe the RedHat PAM package has a similiar option..
I already thought of it and I think that linux _should_ be more protected against such kind of attacks. A simple solution: If there's no swap space, the kernel should count which user is taking most memory and kill some his processes; not just kill the first process that actually wants memory over limit.
Mikulas Patocka
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