[tproxy] tproxy can't work with ip_conntrack

[NTPT]

I thing there is no need to track connction from client to TPROXY server.

And what about to move -m socket match and other stuff to the raw conntrack table  and then use a -j NOTRACK target to selectively  do not conntrack connections from client to tproxy server, while other connections, include from tproxy server to the world , will be still conntracked ? 

please  execuse my wrong english


# ------------ Původní zpráva ------------
# Od: KOVACS Krisztian <hidden at sch.bme.hu>
# Předmět: Re: [tproxy] tproxy can't work with ip_conntrack
# Datum: 22.10.2008 17:30:04
# ----------------------------------------
# Hi,
# 
# On sze, okt 22, 2008 at 04:11:09 +0800, Dong Wei wrote:
# > >> I think that we can add some new fields to identify the two HTTP
# > >> connections in ip_conntrack structure(one is Client->TPROXY Server,
# > >> and the other is TPROXY Server->HTTP Server).
# > >> I hope we can get the right conntrack when we just know the tuple
# > >> containing src_ip,src_port,dst_ip,dst_port. Because there is lots of
# > >> kernel code like this:
# > >>
# > >> 1. get the tuple 4 fields(src_ip,src_port,dst_ip,dst_port) from skb
# > >> 2. call: nf_conntrack_find_get(tuple) to find the corresponding
# ip_conntrack.
# > >> So in this case we can only know the 4 fields, we can't get any more
# > >> message from skb.
# > >>
# > >> Assuming there are 2 ip_conntrack:
# > >> [1]: 192.168.2.2:12345->192.168.1.2:80(client->TPROXY Server)
# > >> [2]: 192.168.2.2:12345->192.168.1.2:80(TPROXY Server->HTTP Server)
# > >> When we process TCP packets between client and TPROXY Server, we find
# > >> the conntrack for 192.168.2.2:123456->192.168.1.2:80, the result
# > >> should
# > >> be [1], and if the TCP packets belong to TPROXY Server and HTTP Server
# > >> connection, the result should be [2]
# > >>
# > >> Does anyone have good idea about the requirement mentioned above?
# > >
# > > I think most users work around the problem: you usually don't really
# > > need the source port to be preserved exactly and by choosing a different
# > > source port the problem goes away.
# > >
# > > (If you don't care about the source port then bind the socket to port 0
# > > and the kernel will choose an unused port.)
# > 
# > Thanks for your reply.  But, I think maybe this solution still have problems.
# > 
# > Here is a sample:
# > Client -> TPROXY Server (192.168.2.2:12345 ->192.168.1.2:80)
# > TPROXY Server -> HTTP Server(192.168.2.2:54321->192.168.1.2:80)
# > Now the two connections have different ip_conntrack. TPROXY Server use
# > port 54321 instead of 12345 as src port
# > 
# > Next time, the client connect to the HTTP Server
# > Client -> HTTP Server(192.168.2.2:54321 -> 192.168.1.2:80).
# > Now Client use the port 54321 connecting to 192.168.1.2:80(This is
# > common for a NAT server connecting to the same HTTP Server using
# > different src port)
# > When  TPROXY receive this packet, and find ip_conntrack. It will match
# > the old one - TPROXY Server -> HTTP Server.
# > 
# > This still exist the ip_conntrack conflict.
# 
# Yes, and unfortunately you can't do much about that if you're using
# connection tracking. (Except for implementing some method of
# differentiating between the two conntracks in ip_conntrack/nf_conntrack,
# of course.)
# 
# -- 
# KOVACS Krisztian
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