On 07/09/2016 18:39, Grant wrote: >>>>>> Hi, my site is being ravaged by an IP but dropping the IP via >>>>>> shorewall is seeming to have no effect. I'm using his IP from nginx >>>>>> logs. IP blocking in shorewall has always worked before. What could >>>>>> be happening? >>>>> >>>>> >>>>> I'm blocking like this with the firewall running on the web server: >>>>> >>>>> /etc/shorewall/rules >>>>> DROP net:1.2.3.4 $FW >>>>> >>>>> Could shorewall/iptables see a different IP address than the one seen by >>>>> nginx? >>>> >>>> >>>> Most likely the file is configured but the firewall service wasn't >>>> restarted or the rules no loaded. >>> >>> >>> I restarted shorewall plenty. :) I believe the issue was either a >>> persistent connection which conntrack-tools would have allowed me to >>> flush, or my blocking in /etc/shorewall/rules instead of >>> /etc/shorewall/blrules, or both. >>> >> >> What exactly is your issue? That is, what makes you think you even >> have an issue? >> >> The reason I ask is that all iptables is going to do is drop packets >> when they reach the kernel. They still go through your network and >> network card and consume some CPU (even more if you're logging them). >> If you're being flooded by a very large volume of packets then that >> will saturate your connection and simply dropping them at the server >> won't fix the latency this will cause for the good packets. In such >> an attack you need to block those packets as far upstream as you can >> before connections start getting saturated. This might be outside of >> your network perimeter. This is why DDoS attacks are so potent, if >> you use something like fail2ban to just set iptables are done you're >> fixing the barn doors after the horses have already left. > > > I said I was under attack but it was really just an unthrottled and > very greedy bot. fail2ban would have gotten him. But while we're on > the subject, how would you recommend thwarting a DDoS attack against a > dedicated server in a hosted environment? Cloudflare?
A proper DDos? Phone your ISP and ask them to help you. You almost certainly don't have the resources. -- Alan McKinnon alan.mckin...@gmail.com
