[Bro] Connections in conn.log

Marcin Nawrocki marcin.nawrocki at fu-berlin.de
Fri May 19 10:21:36 PDT 2017

Hello bro community,

are all connection attempts recorded in conn.log? Let us assume I am 
monitoring interface eth0, will I see every connection in this log file ...

   * ...independent of the transport layer protocol (udp,tcp,mptcp...) 
and its properties (ports)
   * ...independent of firewalls like iptables blocking incoming packets 
on eth0
   * ...independent of firewalls like iptables forwarding incoming 
packets on eth0 to special targets like NFQUEUE and libnetfilter_queue

Regards, Marcin

Am 18-May-17 um 17:31 schrieb mike anastasakis:
> Hello,
> I have a question regarding how the connections are created in conn.log.
> I thought that the combination tuple o (src_ip, src_port, dest_ip, 
> dest_port)was used to define one connection but this is not the case.
> From my conn.log file I have 6 connections with 6 unique 
> different uids but with the same exact combination tuple mentioned above.
> The first connection is the one that establishes the ssl connection 
> and the other 5 are identified as *OTH *which is No /SYN seen, just 
> midstream traffic (a “partial connection” that was not later closed)./
> /
> /
> Are they not all included in the same connection because bro did not 
> identify the ssl connection closing? If so, does this mean that bro 
> considers a flow as a unique connection if there is a problem protocol 
> beggining and ending?
> Kind Regards,
> Michael
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