netdev - Re: [PATCH -next crap] net: icmp: work around bogus pmtu errors

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Message-Id: <20150714.154009.1071789496366560900.davem@davemloft.net>
Date:	Tue, 14 Jul 2015 15:40:09 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	fw@...len.de
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH -next crap] net: icmp: work around bogus pmtu errors

From: Florian Westphal <fw@...len.de>
Date: Sat, 11 Jul 2015 01:56:49 +0200

> sometimes tcp connections seem to hang.
> tcpdump shows broken path mtu reports.  This "fix" avoids hang and gives:
> 
> [633.327834] icmp: 192.0.0.2 reports mtu 1474 for packet size 1474 to host 204.236.132.12
> [635.586945] icmp: 192.0.0.2 reports mtu 1474 for packet size 1474 to host 54.219.255.254
> [647.106708] icmp: 192.0.0.2 reports mtu 1474 for packet size 1466 to host 204.236.132.12
> [663.084586] icmp: 192.0.0.2 reports mtu 1474 for packet size 1466 to host 54.219.255.254
> 
> sigh.
> 
> Signed-off-by: Florian Westphal <fw@...len.de>
> ---
>  Might be caused by DS-LITE.  I either need the turd below or iptables TCPMSS
>  mangling rules to artificially lower received mss.
> 
>  I don't mind if this is rejected; I'm mostly wondering if anyone
>  else came across suprise like this.

I think the culprit should be identified and fixed ASAP, the last thing we want
is for every system add a hack like this.
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