Messages in this thread | | | Date | Tue, 3 Mar 2009 20:27:47 +0100 | From | martin f krafft <> | Subject | Re: /proc/sys/net/ip*/conf/all/* does not actually affect interfaces |
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also sprach Philipp Matthias Hahn <pmhahn@titan.lahn.de> [2009.03.03.0800 +0100]: > "all" on the other hand allways gets applied in addition to the current > setting, but it depends on the exact setting, if its ORed, ANDed, or > whatevered: [...]
Oh wow. This is very underdocumented. Thanks Philipp for taking the time to reply!
The only reference I could find was
http://lkml.indiana.edu/hypermail/linux/kernel/0103.0/0440.html
which was unanswered.
Can anyone recall the rationale for this somewhat complex-seeming solution?
I suppose the goal is to allow all/* to override (which would be the right solution). However, it depends on whether the default is 0 or 1 on whether to AND or OR. Example:
> log_martians OR
default off, to turn it on globally, I just need to set all=1 and the OR takes care of it.
> rp_filter AND
default on, but to disable it globally (set all=0), it needs the AND.
> (see include/linux/inetdevice.h:83 for IN_DEV_{AND,OR,MAX}CONF)
Unfortunately, that's just ipv4/conf/* and I cannot seem to find the ipv6/conf/* counterparts.
> Putting a new value in "all" doesn't change the value you read > from "$interface", but it only gets computed and used internally.
Hm, that clears it up... kinda. It does *not* explain by the RAs were still accepted (ipv6.conf.all.accept_ra and .autoconf where both 0), so unless those values are (wrongly) OR'd, I will need to investigate this.
I will also work on patches to fix the documentation of this, and that involves the kernel source as well as e.g. the IPv6 HOWTO and other docs and manpages.
But to do this, I'd really like to know a bit more about the design motivation. Anyone?
-- martin | http://madduck.net/ | http://two.sentenc.es/ before he died, rabbi zusya said: "in the world to come they will not ask me, 'why were you not moses?' they will ask me, 'why were you not zusya?'" spamtraps: madduck.bogus@madduck.net [unhandled content-type:application/pgp-signature] | |