Date: Fri, 16 Nov 2001 23:46:18 -0500 (EST) From: PaZt <pazt@razor.tuxtendo.nl> To: xmen koh <xmenkoh@yahoo.com> Cc: <freebsd-security@FreeBSD.ORG> Subject: Re: How to stop DoS Attack?? Message-ID: <Pine.LNX.4.33.0111162342080.28963-100000@razor.tuxtendo.nl> In-Reply-To: <20011116063032.77688.qmail@web20904.mail.yahoo.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, 15 Nov 2001, xmen koh wrote: > > Dear security expert, > > Recently I got a DoS on my web server. Does anyone > know how to > stop a DoS attack and prevent it from happen again? > Some help > will be appreciated to explain the below TCPDump which > I got > during the attack. > > Here are some of my finding during the attack... > > 1) There are a lot of connection from different IP at > the same > time, which tries to overload the system using HTTP > by non- > stop requests of URLs. Below is the TCPDUMP. > > 2) The URLs requested as logged by the web server log > seems to > be quite valid, indicating that the attacker has > studied the > victim web site and many of these requests are for > graphic > files, indicating a planned intention to clog up > the server > & network. > > 3) Many source IPs, suspected all to be forged. > > 4) A very close time between each packet timestamp > indicates a > script is used for this attack. > > Well, a small DDoS could be stopped by a simple firewall, yet a complex or very big DDoS attack is rather hard to stop, maybe even impossible. If the DDoS isnt all too wisely set up, snort (/usr/ports/security/snort) could find the ips where the dos is coming from, wich would make you able to send abuse mails or whatever. That's about all i can think of right now, Grtz, PaZt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.LNX.4.33.0111162342080.28963-100000>