[nSLUG] rsync questions

George N. White III gnwiii at gmail.com
Wed Feb 23 15:31:37 AST 2011

On Wed, Feb 23, 2011 at 3:44 AM, Mike Spencer <mspencer at tallships.ca> wrote:
> [...]
> Daniel Morrison <draker at gmail.com> added:
> dm> An rsync server is also faster than using rsync over ssh, as you
> dm> skip the encryption step. But you should do this only if you trust
> dm> your local network....Since you are using NFS, you must trust your
> dm> local network (right?)
> Faster would be good because my router is old and slow (retained
> because it has a parallel port for a print server).  As I write, rsync
> is reporting between 500 and 600kB/sec using ssh.
> My LAN is probably secure. My net connection is dial-up, not through
> the same router that supports the LAN.  My wireless signal is only
> usable at 150' or less (I've tested it) without better than average
> antenna anyhow.  The nearest neighbor is way further than that. So
> snoopers will have to be close enough (say, parked conspicuously in my
> laneway) to risk my deployment of um.... analog countermeasures. :-)

A friend used to work at one of the US National Laboratories.  He was
discussing some potential security issues and was told "we have assets
to deal with that eventuality".

There are certainly some dedicated snoopers who use better antennas
to hack into corporate sites from outside the property line, but do they
have a reason to be interested in your network?  With dialup they can't
do much spamming or serve much porn, but someone wanting to
upload a small sensitive document might be happy to find an
unsecured rural site with dialup access.

If you haven't already done so, look into mac address filtering in the
wireless router.

> dm> The default for rsync is to skip transfers of entire files if the
> dm> file size and timestamp are the same.
> That tidbit is mentioned only in passing in the manpage, under the
> description of the -I flag.  I was wondering what rsync's notion of
> "files are the same" was.
> Initial backup transfer is taking forever.  In the future there will
> not normally be GB quantities of update or new data.  So I'll see how
> the first update goes over ssh.  If that, too, is tediously slow, I'll
> run the daemon on DEST as a matter of course.

For the initial transfer it may be worth the effort to put both disks in
the same system.  After than you can use rsync.

> Rsync, like tar or gcc, is kinduva Swiss Army Knife.  It's very
> helpful to get some pointers when all you want to do is slice
> tomatoes.

George N. White III <aa056 at chebucto.ns.ca>
Head of St. Margarets Bay, Nova Scotia

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