[Rd] Specifying (set of random) port numbers for the help HTML server (Was: Re: Fixing html help port in 2.10)

Duncan Murdoch murdoch at stats.uwo.ca
Sun Oct 18 16:57:17 CEST 2009

On 17/10/2009 12:08 AM, Henrik Bengtsson wrote:
> On Fri, Oct 16, 2009 at 7:54 AM, Duncan Murdoch <murdoch at stats.uwo.ca> wrote:
>> On 10/16/2009 10:39 AM, Dieter Menne wrote:
>>> I noted that the new html-help in 2.10 under Windows uses a random port on
>>> my
>>> computer.
>>> This cause a problem, because when I create a link such as:
>>> this is for one-time use only. Is it possible to fix the port?
>> Not currently.  If you look in tools:::startDynamicHelp you can see how it
>> is set up; you could duplicate that setup as a temporary workaround.  You
>> might be better off to build R with static help instead.  What is the
>> application where you want to be able to give out links?  Perhaps we could
>> consult an environment variable or option() to choose the port instead of
>> leaving it completely random.
>> The reason it is random is the worry that multiple R instances on the same
>> machine might collide.  All processes on the machine see the same ports.
> Related:
> I'd like to suggest an option/environment variable that specifies the
> set of port numbers sampled from, e.g. 6800:6850 or similar.

I've added an option "help.ports" to set this.  It will try your 
specified ports in order; if you want a random selection, permute them 
yourself, e.g.

options(help.ports = sample(6800:6850))

This will make it into 2.10.0.

Duncan Murdoch

> The reason is that in some places, the user don't have admin
> privileges on the computer and most/all ports are blocked from running
> servers, and there is a sysadm that needs to approve each port to be
> unblocked.  With such a security polices it is possible to have the
> smaller set of port number unblocked (but not the full 0-65535 range).
>  This applies at least to "regular users" on Windows.
> My $.02
> /Henrik
>> Duncan Murdoch
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