Security Basics mailing list archives
RE: Preventing DDOS Syn floods on HTTP servers
From: "Kathmann, Nicholas" <Nicholas.Kathmann () KaiserAl com>
Date: Thu, 11 Mar 2004 09:01:51 -0600
On windows: HKLM\System\CurrentControlSet\Services\Tcpip\Parameters\SynAttachProtect (REG_DWORD) - set to 2 HKLM\System\CurrentControlSet\Services\Tcpip\Parameters\TcpMaxHalfOpenRetire d(REG_DWORD) - Set to 80 This will provide some protection, but won't stop any big attack. You should try to block that type of traffic at your perimeter defenses (most likely the firewall). Nick -----Original Message----- From: Aditya, ALD [Aditya Lalit Deshmukh] [mailto:aditya.deshmukh () online gateway technolabs net] Sent: Tuesday, March 09, 2004 11:18 PM To: nabi1 () securology org; security-basics () securityfocus com Subject: RE: Preveting DDOS Syn floods on HTTP servers
I was wondering if it was possible for a HTTP servers to prevent DDOS syn floods, attacks from different IP's, like a attack from a IRC network or something like that.
if you are using linux look into tcp_syncookies, a word of caution : it requires a lot of physical memory and this allocated memory is non swappable. increasing the value by a small bit would cause quite a bit of increase in memory requirments but your server would be able to handle syn floods more efficiently. HTTP server cannot be hardened because syn scans are to be blocked by the os : so harden your OS -aditya ________________________________________________________________________ Delivered using the Free Personal Edition of Mailtraq (www.mailtraq.com) --------------------------------------------------------------------------- Ethical Hacking at the InfoSec Institute. Mention this ad and get $545 off any course! All of our class sizes are guaranteed to be 10 students or less to facilitate one-on-one interaction with one of our expert instructors. Attend a course taught by an expert instructor with years of in-the-field pen testing experience in our state of the art hacking lab. Master the skills of an Ethical Hacker to better assess the security of your organization. Visit us at: http://www.infosecinstitute.com/courses/ethical_hacking_training.html ---------------------------------------------------------------------------- --------------------------------------------------------------------------- Ethical Hacking at the InfoSec Institute. Mention this ad and get $545 off any course! All of our class sizes are guaranteed to be 10 students or less to facilitate one-on-one interaction with one of our expert instructors. Attend a course taught by an expert instructor with years of in-the-field pen testing experience in our state of the art hacking lab. Master the skills of an Ethical Hacker to better assess the security of your organization. Visit us at: http://www.infosecinstitute.com/courses/ethical_hacking_training.html ----------------------------------------------------------------------------
Current thread:
- RE: Preventing DDOS Syn floods on HTTP servers Kathmann, Nicholas (Mar 11)