On 07/10/2017 01:25 AM, Vieri Di Paola via Shorewall-users wrote:
> Hi,
> 
> I'm getting a considerable amount of log messages such as this one:
> 
> kernel: Shorewall:dropNotSyn:DROP:IN=enp9s6 OUT=
> MAC=00:0d:88:cd:7f:c6:50:67:f0:af:f4:57:08:00 SRC=173.194.153.82
> DST=192.168.101.2 LEN=40 TOS=0x00 PREC=0x00 TTL=49 ID=29119 PROTO=TCP
> SPT=443 DPT=58079 WINDOW=0 RES=0x00 RST URGP=0 MARK=0x3
> 
> What does it mean exactly?
> 

This happens when Netfilter believes that flow is closed and deletes the
conntrack entry, while one of the end-points still thinks that the flow
is alive and sends an RST. In my own ruleset, I handle this with:

        RST(ACCEPT)     { SOURCE=all, DEST=all }

I have also seen similar problems with SYN,PSH,ACK packets, and added a
FIN action in 5.1.5. I use it similarly:

        FIN(ACCEPT)     { SOURCE=ALL, DEST=all }

-Tom
-- 
Tom Eastep        \   Q: What do you get when you cross a mobster with
Shoreline,         \     an international standard?
Washington, USA     \ A: Someone who makes you an offer you can't
http://shorewall.org \   understand
                      \_______________________________________________

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