From: NeilBrown <neilb@suse.com>
To: Joachim Banzhaf <joachim.banzhaf@googlemail.com>,
        linux-nfs@vger.kernel.org
Date: Fri, 02 Dec 2016 11:14:38 +1100
Cc: "joachim.banzhaf" <joachim.banzhaf@googlemail.com>
Subject: Re: rpcbind allowed port range on linux
In-Reply-To: <CABW3MLd5Bo-xBtLqtB4e-pD2hCYAuRaBBsqBFTiws5-HohjPTw@mail.gmail.com>
References: <CABW3MLd5Bo-xBtLqtB4e-pD2hCYAuRaBBsqBFTiws5-HohjPTw@mail.gmail.com>
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On Fri, Dec 02 2016, Joachim Banzhaf wrote:

> Hi list,
>
> my problem is, rpcbind gave a tcp port to nlockmgr where I assumed
> this port is reserved.

That isn't how it works. rpcbind doesn't give ports to anyone.

lockd chooses a port, and asks rpcbind to register it against the
nlockmgr service.
If lockd is choosing a port that you don't want it to, you need to
get lockd to change its behavior.

One way is to explicitly tell lockd what port to use.  The "--nlm-port"
option to rpc.statd can do this.

By default, a number will be chosen from the range given in
  /proc/sys/net/ipv4/ip_local_port_range=20

You can change that range, and that will affect all sockets which don't
ask for an explicit port.

NeilBrown


>
> Now, I didn't find the spec that says which ports rpcbind is allowed
> to use, but I thought it is the ephemeral ports, on linux defined with
> the range in kernel configuration net.ipv4.ip_local_reserved_ports
> minus exclusions from net.ipv4.ip_local_reserved_ports.
>
> So, my questions are
> 1) Is my assumption about allowed ports correct?
> 2) If not: how can I define that range?
> 3) If yes: was there a fix for that since my rather old SLES 12
> version rpcbind-0.2.1_rc4 (kernel 3.12.55)? I didn't find something
> obvious to me in the changelog.
>
> Bonus question: would it have been safe/possible to free up the port,
> e.g. with rpcbind -d? I only found out about that option after a
> reboot...
>
> BR,
> Joachim
>
> (please keep me in cc)
> --
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