Date: Fri, 04 Jan 2002 15:11:45 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Guido van Rooij <guido@gvr.org> Cc: William Carrel <william.carrel@infospace.com>, freebsd-hackers@freebsd.org Subject: Re: path_mtu_discovery Message-ID: <3C3636B1.4D5F42A4@mindspring.com> References: <26E71536-013D-11D6-8ED3-003065D5E9A4@infospace.com> <3C36149B.B9C02DCF@mindspring.com> <20020104223235.GA64301@gvr.gvr.org>
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Guido van Rooij wrote: > > > ipfilter with 'keep state' on the connections will automatically allow > > > back in relevant ICMP messages such as mustfrag. > > > > Heh... I need to try to write a "mustfrag" daemon, which will > > spoof them back whenever it sees traffic... and see what happens. > > The sender will start sending smaller segments. That's it. > But if you are in the patch between sender and receiver you can do worse > things than that. I knew that I could multiply the number of packets sent by a factor of 5... I was pointing out a flaw in the idea of allowing path MTU ICMP back in, unconditionally... Now ask me how to DOS attack any server daemon that works by using the "sendfile" interface... PS: *Don't* ask me how the SYN-cache overflow SYN-cookie code can be ACK-flooded, to make the kernel spend all its time doing MD5 calculations, since that one is obvious... -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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