Re: [PATCHv4] extensions: libxt_CHECKSUM extension

From: Patrick McHardy
Date: Thu Jul 15 2010 - 11:24:40 EST


Am 15.07.2010 13:52, schrieb Michael S. Tsirkin:
> 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

Applied to iptables-next, thanks.
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