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| author | Thomas Graf <tgraf@suug.ch> | 2012-06-12 00:44:01 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-06-12 15:25:46 -0700 |
| commit | d0daebc3d622f95db181601cb0c4a0781f74f758 (patch) | |
| tree | cbce3159c160d49675dba0d720d186be7f0d79d3 /net/ipv4/devinet.c | |
| parent | 0440507bbc44149e63bbfb9df730ba3820371904 (diff) | |
| download | linux-stable-d0daebc3d622f95db181601cb0c4a0781f74f758.tar.gz linux-stable-d0daebc3d622f95db181601cb0c4a0781f74f758.tar.bz2 linux-stable-d0daebc3d622f95db181601cb0c4a0781f74f758.zip | |
ipv4: Add interface option to enable routing of 127.0.0.0/8
Routing of 127/8 is tradtionally forbidden, we consider
packets from that address block martian when routing and do
not process corresponding ARP requests.
This is a sane default but renders a huge address space
practically unuseable.
The RFC states that no address within the 127/8 block should
ever appear on any network anywhere but it does not forbid
the use of such addresses outside of the loopback device in
particular. For example to address a pool of virtual guests
behind a load balancer.
This patch adds a new interface option 'route_localnet'
enabling routing of the 127/8 address block and processing
of ARP requests on a specific interface.
Note that for the feature to work, the default local route
covering 127/8 dev lo needs to be removed.
Example:
$ sysctl -w net.ipv4.conf.eth0.route_localnet=1
$ ip route del 127.0.0.0/8 dev lo table local
$ ip addr add 127.1.0.1/16 dev eth0
$ ip route flush cache
V2: Fix invalid check to auto flush cache (thanks davem)
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/devinet.c')
| -rw-r--r-- | net/ipv4/devinet.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index 10e15a144e95..44bf82e3aef7 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -1500,7 +1500,8 @@ static int devinet_conf_proc(ctl_table *ctl, int write, if (cnf == net->ipv4.devconf_dflt) devinet_copy_dflt_conf(net, i); - if (i == IPV4_DEVCONF_ACCEPT_LOCAL - 1) + if (i == IPV4_DEVCONF_ACCEPT_LOCAL - 1 || + i == IPV4_DEVCONF_ROUTE_LOCALNET - 1) if ((new_value == 0) && (old_value != 0)) rt_cache_flush(net, 0); } @@ -1617,6 +1618,8 @@ static struct devinet_sysctl_table { "force_igmp_version"), DEVINET_SYSCTL_FLUSHING_ENTRY(PROMOTE_SECONDARIES, "promote_secondaries"), + DEVINET_SYSCTL_FLUSHING_ENTRY(ROUTE_LOCALNET, + "route_localnet"), }, }; |