I'm doing it right now, should be ready tomorrow. On Sun, Sep 6, 2009 at 12:32 AM, Kenny Loggins<[email protected]> wrote: > I'm willing to pay someone to write a windows version of a query proxy. > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Saul Rennison > Sent: Saturday, September 05, 2009 4:36 PM > To: Half-Life dedicated Win32 server mailing list > Subject: Re: [hlds] TF2 DDOS AS2_INFO attack > > This is why A2S_INFO requires a challenge :| > > Thanks, > - Saul. > > > 2009/9/5 Matt Stanton <[email protected]> > >> If these attacks are coming from ips that are outside of the range of >> your standard users' network range, then it's possible you could filter >> out requests from unallocated ip blocks and ip blocks from areas of the >> internet that are gnerally too far away to have decent latency on your >> server. Unfortunately, this would mean building a database of ip blocks >> that are allocated to networks that are within a reasonable distance of >> your server's network and checking every A2S_INFO packet that comes in >> against this database, which would likely eat a decent amount of CPU. >> >> Nephyrin Zey wrote: >> > The bandwidth involved in this attack is tiny. The issue is srcds chokes >> > on large numbers of A2S_INFO packets, its not the traffic that's doing >> > machines in. I'd reckon a single residential connection could take down >> > a server this way. Once you fix the srcds issue, the problem stops. I >> > have a daemon that intercepts server queries and handles them itself. >> > It's currently handling this attacker hammering on two servers without >> > breaking 1% CPU or making a single-pixel dent in my bandwidth graphs, >> > and my tf2 servers continue to run just fine. >> > >> > And if you actually examine the attack, it's very obviously a single >> > source with spoofed IPs. I rather doubt someone has a million-strong >> > botnet containing nearly 30% unallocated IP ranges, that all happen to >> > have the same exact path length. >> > >> > - Neph >> > >> > On 09/05/2009 12:50 PM, [email protected] wrote: >> > >> >> This... actually isn't a bad idea. It's a pain to implement, though, >> for a >> >> couple of reasons. >> >> >> >> First, the assumption by most on this thread is that it's a single guy >> >> operating from a single (or just a handful) of computers. They further >> >> assume that he's forging the source IP addresses so the requests look >> like >> >> they're coming from many many different machines. If this is true, >> there's >> >> no way to trace or block him based upon the information included in the >> >> packets he's creating. I think this assumption is wrong, as I'll >> explain >> >> below. >> >> >> >> Second, if this assumption is incorrect you need to find a way to >> identify >> >> each and every source and block them one at a time. Netblocks are at >> best a >> >> crude measure which risks blocking many legitimate clients. Such a >> process >> >> needs to be automated as much as possible or it's not effective. >> >> >> >> Now, why do I think that this is probably not coming from just a > handful >> of >> >> sources? Simple. DDoS stands for Distributed Denial of Service, after >> >> all. Botnets are reaching incredible proportions. It's easy to rent > as >> >> many as a quarter million compromised machines if you want to and you >> have >> >> the cash. >> >> >> >> Too cheap or too poor to rent someone else's network of infected PCs? >> No >> >> problem. Tools exist to build new malware and they're easy to come by >> if >> >> you're willing to start looking in the right places. All you have to > do >> is >> >> build your bot code and figure out a way to get it loaded on 5,000, >> 10,000, >> >> or more PCs. After that, DDoS to your heart's content. Script kiddies >> do >> >> this _all_ _the_ _time_. >> >> >> >> So, when under attack your choices are: >> >> >> >> * Wait it out. >> >> >> >> * Work with your vendor to figure out a way block the attack in the >> first >> >> place. (Valve, obviously, in this case.) >> >> >> >> * Automate the process of identifying sources and filtering them out. >> >> >> >> * Cry a lot. >> >> >> >> Generally, I settle for a combination of the first and second options. >> If >> >> an attack gets bad enough, I work with my local ISP to implement the >> third. >> >> (My server is co-located in their datacenter and they're really good >> guys to >> >> work with.) Generally, some combination of tcpwrapper, netfilter, and >> >> iptables will do the job on my Linux server. Sometimes we find it >> easier to >> >> just block it at one of their routers so they don't have to deal with >> the >> >> traffic on their network. >> >> >> >> Every now and again, I find myself following the fourth option until I >> >> figure out what's going on and fall back on some combination of the >> first >> >> three options. :-) >> >> >> >> HTH. >> >> >> >> =JpS=SgtRock >> >> >> >> >> > >> > _______________________________________________ >> > To unsubscribe, edit your list preferences, or view the list archives, >> please visit: >> > http://list.valvesoftware.com/mailman/listinfo/hlds >> > >> > >> >> >> _______________________________________________ >> To unsubscribe, edit your list preferences, or view the list archives, >> please visit: >> http://list.valvesoftware.com/mailman/listinfo/hlds >> > _______________________________________________ > To unsubscribe, edit your list preferences, or view the list archives, > please visit: > http://list.valvesoftware.com/mailman/listinfo/hlds > > > > _______________________________________________ > To unsubscribe, edit your list preferences, or view the list archives, please > visit: > http://list.valvesoftware.com/mailman/listinfo/hlds >
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