[PATCH] ip.7: add IP_BIND_ADDRESS_NO_PORT description

[PATCH] ip.7: add IP_BIND_ADDRESS_NO_PORT description

[Eric Dumazet]

From: Eric Dumazet <edumazet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

Documentation for IP_BIND_ADDRESS_NO_PORT socket option
added in linux-4.2
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=90c337da1524863838658078ec34241f45d8394d

Signed-off-by: Eric Dumazet <edumazet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
---
 man7/ip.7 |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/man7/ip.7 b/man7/ip.7
index 1c51a50..f8d4e63 100644
--- a/man7/ip.7
+++ b/man7/ip.7
@@ -338,6 +338,11 @@ application wants to receive data from.
 This option can be used multiple times to allow
 receiving data from more than one source.
 .TP
+.BR IP_BIND_ADDRESS_NO_PORT " (since Linux 4.2)
+Instruct kernel to not reserve an ephemeral port at bind() time.
+The port will be automatically chosen at connect() time, in a way
+that allows sharing a source port as long as the 4-tuples are unique.
+.TP
 .BR IP_BLOCK_SOURCE " (since Linux 2.4.22 / 2.5.68)"
 Stop receiving multicast data from a specific source in a given group.
 This is valid only after the application has subscribed


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Re: [PATCH] ip.7: add IP_BIND_ADDRESS_NO_PORT description

[Michael Kerrisk (man-pages)]

Hi Eric,

On 02/02/2016 12:35 AM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> 
> Documentation for IP_BIND_ADDRESS_NO_PORT socket option
> added in linux-4.2
> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=90c337da1524863838658078ec34241f45d8394d

Thanks for the patch. I've applied, and tweaked a little.
It would be good to add a couple of sentences about
why this option is useful and what use case it allows.
Could you come up with something?

Thanks,

Michael

PS How about a patch for SO_MAX_PACING_RATE for the socket(7) page :-) ?

> Signed-off-by: Eric Dumazet <edumazet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> ---
>  man7/ip.7 |    5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/man7/ip.7 b/man7/ip.7
> index 1c51a50..f8d4e63 100644
> --- a/man7/ip.7
> +++ b/man7/ip.7
> @@ -338,6 +338,11 @@ application wants to receive data from.
>  This option can be used multiple times to allow
>  receiving data from more than one source.
>  .TP
> +.BR IP_BIND_ADDRESS_NO_PORT " (since Linux 4.2)
> +Instruct kernel to not reserve an ephemeral port at bind() time.
> +The port will be automatically chosen at connect() time, in a way
> +that allows sharing a source port as long as the 4-tuples are unique.
> +.TP
>  .BR IP_BLOCK_SOURCE " (since Linux 2.4.22 / 2.5.68)"
>  Stop receiving multicast data from a specific source in a given group.
>  This is valid only after the application has subscribed
> 
> 
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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Re: [PATCH] ip.7: add IP_BIND_ADDRESS_NO_PORT description

[Eric Dumazet]

On Wed, 2016-02-03 at 15:49 +0100, Michael Kerrisk (man-pages) wrote:
> Hi Eric,
> 
> On 02/02/2016 12:35 AM, Eric Dumazet wrote:
> > From: Eric Dumazet <edumazet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> > 
> > Documentation for IP_BIND_ADDRESS_NO_PORT socket option
> > added in linux-4.2
> > http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=90c337da1524863838658078ec34241f45d8394d
> 
> Thanks for the patch. I've applied, and tweaked a little.
> It would be good to add a couple of sentences about
> why this option is useful and what use case it allows.
> Could you come up with something?

Well, port exhaustion is something hard to explain in a few words ;)

https://idea.popcount.org/2014-04-03-bind-before-connect/ is explaining
the problem quite well (but was written before IP_BIND_ADDRESS_NO_PORT
came)

Sure, I will post something about SO_MAX_PACING_RATE

Thanks.


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