linux-kernel - Unexpected tcpv6 connection resets since linux 4.4

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Message-ID: <4875526.tAzumr2zO3@proton>
Date:	Sun, 06 Mar 2016 16:10:07 +0100
From:	Andreas Messer <andi@...telmap.de>
To:	linux-kernel@...r.kernel.org
Subject: Unexpected tcpv6 connection resets since linux 4.4

Hi there,

i have updated two of my machines in the last weeks to linux 4.4.1 and linux 
4.4.3. It seems that since then i get unexpected TCPv6 connection resets when 
connecting to these machines remotely. The issue occurs with sshd and with a 
http service. /etc/hosts.deny and /etc/hosts.allow are empty on both server 
machines. I'm not so in IPv6 and have no idea whats going on. Please find 
attached a network trace from one of the machines when connecting with ssh (on 
port 23 for debugging). 

Redirects should be accepted according to settings:

root@...ana:/proc/sys/net/ipv6# cat conf/wlan0/forwarding 
0
root@...ana:/proc/sys/net/ipv6# cat conf/wlan0/accept_redirects 
1
root@...ana:/proc/sys/net/ipv6# uname -a
Linux banana 4.4.1-banana #3 SMP Wed Feb 17 23:03:38 CET 2016 x86_64 GNU/Linux

Is there some new network settings or features? My network consists of an 
ethernet/wlan router where subnet of wlan and ethernet are identical.  (forced 
by the router, but was never a problem before). The problem occurs when 
connecting from ethernet machine to wlan machine and when connecting from wlan 
machine to wlan machine. At the moment its not possible to establish a 
connection with these machines using IPv6.

Thanks for help!

Cheers
Andreas
Download attachment "ipv6_rst_after_redirect.pcapng" of type "application/x-pcapng" (1660 bytes)