netdev - Re: [PATCH net-next] net: tcp_probe: allow more advanced ingress filtering by mark

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Date:	Fri, 23 Aug 2013 08:13:33 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Daniel Borkmann <dborkman@...hat.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] net: tcp_probe: allow more advanced ingress
 filtering by mark

On Fri, 2013-08-23 at 16:16 +0200, Daniel Borkmann wrote:
> Currently, the tcp_probe snooper can either filter packets by a given
> port (handed to the module via module parameter e.g. port=80) or lets
> all TCP traffic pass (port=0, default). When a port is specified, the
> port number is tested against the sk's source/destination port. Thus,
> if one of them matches, the information will be further processed for
> the log.
> 
> As this is quite limited, allow for more advanced filtering possibilities
> which can facilitate debugging/analysis with the help of the tcp_probe
> snooper. Therefore, similarly as added to BPF machine in commit 7e75f93e
> ("pkt_sched: ingress socket filter by mark"), add the possibility to
> use skb->mark as a filter.
> 
> If the mark is not being used otherwise, this allows ingress filtering
> by flow (e.g. in order to track updates from only a single flow, or a
> subset of all flows for a given port) and other things such as dynamic
> logging and reconfiguration without removing/re-inserting the tcp_probe
> module, etc. Simple example:
> 
>   insmod net/ipv4/tcp_probe.ko fwmark=8888 full=1
>   ...
>   iptables -A INPUT -i eth4 -t mangle -p tcp --dport 22 \
>            --sport 60952 -j MARK --set-mark 8888
>   [... sampling interval ...]
>   iptables -D INPUT -i eth4 -t mangle -p tcp --dport 22 \
>            --sport 60952 -j MARK --set-mark 8888
> 
> The current option to filter by a given port is still being preserved. A
> similar approach could be done for the sctp_probe module as a follow-up.
> 
> Signed-off-by: Daniel Borkmann <dborkman@...hat.com>
> ---

Well, why not adding ability to load/use a BPF filter instead ? ;)



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