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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/arp.c | |
| parent | 0440507bbc44149e63bbfb9df730ba3820371904 (diff) | |
| download | linux-d0daebc3d622f95db181601cb0c4a0781f74f758.tar.gz linux-d0daebc3d622f95db181601cb0c4a0781f74f758.tar.bz2 linux-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/arp.c')
| -rw-r--r-- | net/ipv4/arp.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index cda37be02f8d..2e560f0c757d 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -790,7 +790,8 @@ static int arp_process(struct sk_buff *skb) * Check for bad requests for 127.x.x.x and requests for multicast * addresses. If this is one such, delete it. */ - if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip)) + if (ipv4_is_multicast(tip) || + (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) goto out; /* |