netdev - Re: [PATCH v3] net: Use standardized (IANA) local port range

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200829103715.iofmvtisabjl5hqb@lion.mk-sys.cz>
Date:   Sat, 29 Aug 2020 12:37:15 +0200
From:   Michal Kubecek <mkubecek@...e.cz>
To:     Bart Groeneveld <avi@...tavi.nl>
Cc:     linux-kernel@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        netdev@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v3] net: Use standardized (IANA) local port range

On Fri, Aug 28, 2020 at 10:44:47PM +0200, Bart Groeneveld wrote:
> This change will effectively halve the available ephemeral ports,
> increasing the risk of port exhaustion. But:
> ...
> b) It is only an issue with more than 11848 *outgoing* connections.
> 	I think that is a niche case (I know, citation needed, but still).

You don't need 11848 simultaneous connections to run into problems as
you may also have timewait sockets left after a connection is closed.
If there are many shortlived outgoing connections to the same server,
you may run out of ephemeral ports even without having too many active
connections at any time.

Michal