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authorPaolo Abeni <pabeni@redhat.com>2015-10-09 15:34:31 +0300
committerDavid S. Miller <davem@davemloft.net>2015-10-13 05:38:02 +0300
commite2ca690b657f4ca5c204fcc6470d462b776d73b3 (patch)
treebad7ed1b3899da4affa41704c52c27e0a8a616c0 /Documentation/networking
parent0944d6b5a2fad9ba3b7abb2e94a6b7d40cd4a935 (diff)
downloadlinux-e2ca690b657f4ca5c204fcc6470d462b776d73b3.tar.xz
ipv4/icmp: redirect messages can use the ingress daddr as source
This patch allows configuring how the source address of ICMP redirect messages is selected; by default the old behaviour is retained, while setting icmp_redirects_use_orig_daddr force the usage of the destination address of the packet that caused the redirect. The new behaviour fits closely the RFC 5798 section 8.1.1, and fix the following scenario: Two machines are set up with VRRP to act as routers out of a subnet, they have IPs x.x.x.1/24 and x.x.x.2/24, with VRRP holding on to x.x.x.254/24. If a host in said subnet needs to get an ICMP redirect from the VRRP router, i.e. to reach a destination behind a different gateway, the source IP in the ICMP redirect is chosen as the primary IP on the interface that the packet arrived at, i.e. x.x.x.1 or x.x.x.2. The host will then ignore said redirect, due to RFC 1122 section 3.2.2.2, and will continue to use the wrong next-op. Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/ip-sysctl.txt19
1 files changed, 17 insertions, 2 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index ebe94f2cab98..99838259e2e6 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -884,8 +884,8 @@ icmp_ignore_bogus_error_responses - BOOLEAN
icmp_errors_use_inbound_ifaddr - BOOLEAN
- If zero, icmp error messages are sent with the primary address of
- the exiting interface.
+ If zero, icmp error messages except redirects are sent with the primary
+ address of the exiting interface.
If non-zero, the message will be sent with the primary address of
the interface that received the packet that caused the icmp error.
@@ -897,8 +897,23 @@ icmp_errors_use_inbound_ifaddr - BOOLEAN
then the primary address of the first non-loopback interface that
has one will be used regardless of this setting.
+ The source address selection of icmp redirect messages is controlled by
+ icmp_errors_use_inbound_ifaddr.
Default: 0
+icmp_redirects_use_orig_daddr - BOOLEAN
+
+ If zero, icmp redirect messages are sent using the address specified for
+ other icmp errors by icmp_errors_use_inbound_ifaddr.
+
+ If non-zero, the message will be sent with the destination address of
+ the packet that caused the icmp redirect.
+ This behaviour is the preferred one on VRRP routers (see RFC 5798
+ section 8.1.1).
+
+ Default: 0
+
+
igmp_max_memberships - INTEGER
Change the maximum number of multicast groups we can subscribe to.
Default: 20