DOC: mention the effect of nf_conntrack_tcp_loose on src/dst

On rare occasions the logs may report inverted src/dst when using
conntrack with this sysctl. Add a mention for it in the doc. More
info here :

     https://www.spinics.net/lists/netdev/msg544878.html
This commit is contained in:
Willy Tarreau 2019-01-23 10:02:15 +01:00
parent 526894ff39
commit 64ded3db2c

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@ -14452,7 +14452,12 @@ dst : ip
which is the address the client connected to. It can be useful when running which is the address the client connected to. It can be useful when running
in transparent mode. It is of type IP and works on both IPv4 and IPv6 tables. in transparent mode. It is of type IP and works on both IPv4 and IPv6 tables.
On IPv6 tables, IPv4 address is mapped to its IPv6 equivalent, according to On IPv6 tables, IPv4 address is mapped to its IPv6 equivalent, according to
RFC 4291. RFC 4291. When the incoming connection passed through address translation or
redirection involving connection tracking, the original destination address
before the redirection will be reported. On Linux systems, the source and
destination may seldom appear reversed if the nf_conntrack_tcp_loose sysctl
is set, because a late response may reopen a timed out connection and switch
what is believed to be the source and the destination.
dst_conn : integer dst_conn : integer
Returns an integer value corresponding to the number of currently established Returns an integer value corresponding to the number of currently established
@ -14799,7 +14804,13 @@ src : ip
behind a proxy. However if the "accept-proxy" or "accept-netscaler-cip" bind behind a proxy. However if the "accept-proxy" or "accept-netscaler-cip" bind
directive is used, it can be the address of a client behind another directive is used, it can be the address of a client behind another
PROXY-protocol compatible component for all rule sets except PROXY-protocol compatible component for all rule sets except
"tcp-request connection" which sees the real address. "tcp-request connection" which sees the real address. When the incoming
connection passed through address translation or redirection involving
connection tracking, the original destination address before the redirection
will be reported. On Linux systems, the source and destination may seldom
appear reversed if the nf_conntrack_tcp_loose sysctl is set, because a late
response may reopen a timed out connection and switch what is believed to be
the source and the destination.
Example: Example:
# add an HTTP header in requests with the originating address' country # add an HTTP header in requests with the originating address' country