How can I secure my apache server from DoS attack ?

[Neelesh Gurjar <neel.hjs@xxxxxxxxx>]

Hi,

I have a web server which has CentOS Linux 2.6.18-028stab059.6-ent kernel and Apache 1.3.37 running on it.

2 days back I got one script to test DoS attack on website. It is called slowloris.pl  from http://ha.ckers.org/slowloris/

I run that script against my server and it worked. It stopped my website for some time. That time all other services like SSH were working fine.

Can anybody suggests any configuration changes at Apache and OS/Kernel level to prevent from this type of attack ?

Currently I am using following settings:

Timeout 300

KeepAlive On

MaxKeepAliveRequests 100

KeepAliveTimeout 5

MinSpareServers 5

MaxSpareServers 10

StartServers 5

MaxClients 150

MaxRequestsPerChild 0

Then Kernel settings are like :

tcp_keepalive_time 7200

tcp_keepalive_time 9

tcp_keepalive_intvl 75

tcp_syn_retries 5

tcp_synack_retries 5

tcp_fin_timeout 60

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Regards
NeeleshG

LINUX is basically a simple operating system, but you have to be a genius to understand the simplicity