|author||Michael S. Tsirkin <firstname.lastname@example.org>||2010-07-15 17:23:24 +0200|
|committer||Patrick McHardy <email@example.com>||2010-07-15 17:23:24 +0200|
extensions: libxt_CHECKSUM extension
This adds a `CHECKSUM' target, which can be used in the iptables mangle table. You can use this target to compute and fill in the checksum in a packet that lacks a checksum. This is particularly useful, if you need to work around old applications such as dhcp clients, that do not work well with checksum offloads, but don't want to disable checksum offload in your device. The problem happens in the field with virtualized applications. For reference, see Red Hat bz 605555, as well as http://www.spinics.net/lists/kvm/msg37660.html Typical expected use (helps old dhclient binary running in a VM): iptables -A POSTROUTING -t mangle -p udp --dport bootpc \ -j CHECKSUM --checksum-fill Includes fixes by Jan Engelhardt <firstname.lastname@example.org> Signed-off-by: Michael S. Tsirkin <email@example.com> Signed-off-by: Patrick McHardy <firstname.lastname@example.org>
Diffstat (limited to 'extensions/libxt_CHECKSUM.man')
1 files changed, 8 insertions, 0 deletions
diff --git a/extensions/libxt_CHECKSUM.man b/extensions/libxt_CHECKSUM.man
new file mode 100644
@@ -0,0 +1,8 @@
+This target allows to selectively work around broken/old applications.
+It can only be used in the mangle table.
+Compute and fill in the checksum in a packet that lacks a checksum.
+This is particularly useful, if you need to work around old applications
+such as dhcp clients, that do not work well with checksum offloads,
+but don't want to disable checksum offload in your device.