Date: Tue, 29 Jun 2004 16:44:13 +0100 From: David Malone <dwmalone@maths.tcd.ie> To: Max Laier <max@love2party.net> Cc: freebsd-net@freebsd.org Subject: Re: RANDOM_IP_ID sysctl? Message-ID: <200406291644.aa85787@salmon.maths.tcd.ie> In-Reply-To: Your message of "Tue, 29 Jun 2004 16:43:32 %2B0200." <200406291643.39705.max@love2party.net>
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> > On Tue, Jun 29, 2004 at 02:13:38PM +0100, David Malone wrote: > > > It seems to me that RANDOM_IP_ID might be better as a sysctl rather > > > than a kernel option. Would anyone mind if I changed this? > I personally think that RANDOM_IP_ID is something that should be tweakable on > a per-interface basis (at least). I usually want randomized IDs on my uplink > interface while it could harm my GigE internal network due to faster ID reuse > cycles. Though, on your GigE internal network, you can probably use jumbograms to avoid fragmentation and avoid having to pay any attention to IP IDs ;-) There was code to only bother setting the IP ID for packets with DF set, but that caused certain odd pieces of network kit that ignored DF to be sick... > FYI, pf(4) can set randomized IDs on a per interface (and even on a per > connection) basis. pf is probably the best place for this sort of more flexable IP ID setting. > David, I'd appreciate to review your patches in order to avoid breakage of pf, > thanks. Certainly. > One would clearly transform the now present "#ifdef" with "if (sysctlvar)" > and hence this will not incur overhead (one compare is nothing to worry > about). Yes - this is exactly what I had in mind. I'm certain that the overhead of the extra "if ()" will be lost in the cost of the IP stack. Currently RANDOM_IP_ID also controls other things, such as flow id generation for IPv6. Making it a sysctl would also give us independent control over these things. David.
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