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Date: Wed, 01 Jul 2009 10:56:15 +0200 From: Patrick McHardy <kaber@...sh.net> To: Mark McLoughlin <markmc@...hat.com> CC: netdev <netdev@...r.kernel.org>, Herbert Xu <herbert@...dor.apana.org.au> Subject: Re: [PATCH] bridge: make bridge-nf-call-*tables default configurable Mark McLoughlin wrote: > With BRIDGE_NETFILTER enabled, bridge traffic is passed through > netfilter as it is forwarded across the bridge. This is a useful > feature in specialized cases where the admin wishes to filter bridge > traffic based on higher-level protocol headers. > > However, in a lot of cases, it causes a large amount of confusion > since it is so counter-intuitive - nobody expects their IP firewall > rules to also apply to traffic on their bridges. > > This is especially true for virtualization, where users create a > bridge and find that some types of traffic work and others don't, and > it can take quite some time to identify iptables as the culprit. Users > are often recommended to configure their iptables rules to ACCEPT > "physdev-is-bridged" in order to avoid this confusion. > > However, because nf_conntrack introduces an skb_orphan(), it is now > recommended that bridge-nf-call-iptables be disabled completely so as > to ensure features like TUNSETSNDBUF work as expected. > > For these reasons, it makes sense to allow distributions to disable > netfilter on the bridge by default and require those specialized users > to enable it explicitly via sysctl. I agree that this makes sense, at least temporarily. Mid-term we should really fix the defaults, so it would be good to have a feature-removal-schedule and maybe a runtime warning stating that these defaults will change. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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