[GLLUG] Can anyone explain this netstat output?

John Winters john at sinodun.org.uk
Sun Jun 30 12:00:07 UTC 2019

On 30/06/2019 12:47, Andy Smith via GLLUG wrote:
> Hi John,
> On Sun, Jun 30, 2019 at 11:50:54AM +0100, John Winters via GLLUG wrote:
>> A TCP connection over IPv6 from to  WTF?
> On Linux an AF_INET6 socket can accept both v6 and v4 connections.
> It's mostly down to programmer taste whether to separate the two.
> There is a socket option that can be set to only allow v6 on
> AF_INET6 sockets if the programmer wishes.
>> Note the entries for sshd show two listens - one for IPv4 and one for IPv6
>> which is more what I would expect.
> The BSDs intentionally do not support AF_INET6 sockets accepting
> IPv4 connections and as sshd was ported from OpenBSD, I would think
> that keeping things that way was the path of least resistance.

Hi Andy,

Thanks for that - would seem to explain all the observed symptoms.  So 
useful to find someone who knows what he's talking about.


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