New subject: How can I secure my server from DoS attack ?

24 Jun 2009


      ...
Neelesh Gurjar neel.hjs@gmail.com
wrote:
...
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
mod_evasive, formerly known as mod_dosevasive is a Apache module that
provides evasive maneuvers action in the event of an HTTP DoS or DDoS
(Denial of Service) attack or brute force attack at the web server. When
possible attacks are detected, mod_evasive will block the traffic from the
source for a specific duration of time, while reports abuses via email and
syslog facilities. Or administrators can configure mod_evasive to talk to
iptables, ipchains, firewalls, routers, and etc. to build a comprehensive
DDOS prevention system for the high traffic busy web server.
Else, for Apache 1.3.x,
....
Thanks very much Sameep for all this information.
Regards
Neelesh

Re: [ILUG-BOM] How can I secure my server from DoS attack ?