Date: Wed, 28 May 2003 02:30:16 +0530 (IST) From: "Ashish Kulkarni" <ashish@symonds.net> To: <freebsd-hackers@freebsd.org> Cc: ashish@symonds.net Subject: Re: changing the ToS in IP Header Message-ID: <1392.203.192.199.30.1054069216.squirrel@secure.symonds.net>
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Kenjiro Cho <kjc@csl.sony.co.jp> wrote: > Tell your ISP not to use 0x02; it violates the standard. > You may modify the upper 6 bits for an arbitrary value, though. Well, my cable ISP provides a 3rd party Windows-only client that enables forwarding of packets only when logged in. I've reverse engineering that protocol sucessfully, and it requires the TOS to be 0x02 ... I imagine this TOS is only valid uptil the gateway, after which a different TOS is used. Anyway, all this is unofficial so I can't really go to my ISP and mention it ;-) > The lower 2 bits of the (now deprecated) TOS field are officially > assigned to ECN (RFC3168). 0x02, ECT(0), is used to indicate that the > sender is ECN-capable. > > ALTQ supports diffserv and is capable of rewriting the upper 6 bits of > the TOS field. > http://www.csl.sony.co.jp/~kjc/software.html I have one question: as you said, I can use ALTQ to reset all the upper 6 bits to zero, so as to get the pattern 0x02 (using the kernel patch by Terry Lambert). Will this have any implications for its working and for ECN? I need this because several protocols (ssh, etc) use a modified TOS, which I want to be reset to default value. Thanks, Ashish
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