[Rd] Cross-platform check for internet connection

[Prof Brian Ripley]

On Fri, 22 Jun 2007, hadley wickham wrote:

> What's the recommended way to check if an internet connection is
> available across platforms?  I was using is.null(nsl()) but this does
> not work on windows.

I don't know a way to do this on Windows without a possible very long 
hang.  It's complicated by the use of two alternative internet connection 
mechanisms on Windows and having little control over the IE-based one.

Another issue is software firewalls: they can take many minutes to 
decide to let a new program talk to the Internet if they 'call home' to 
ask advice.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595