hostname doesn't stick

[Matthew Saltzman]

Thanks for the explanation.  That tends to confirm my conjecture and it 
seems to answer at least some of the questions that came up here.

(Top posting because it's just an acknowledgement, so no need to scroll 
down...)

On Mon, 18 Sep 2006, Tim wrote:

> On Mon, 2006-09-18 at 08:24 -0400, Matthew Saltzman wrote:
>> Is there any real harm in having other names associated with the
>> loopback address in /etc/hosts as well?
>
> That rather depends...  You can add other references to itself, and
> they'll work for references to itself.  For standalone PCs, I've done
> that many times without any noticeable problems.
>
> e.g. 127.0.0.1 localhost mywebserver mynewsserver
>
> It might a problem if you were on a network with more than one system,
> and you tried to work between the two of them while one was still using
> an address referring to itself.
>
> It's more of a problem for users, than software, in my experience.  They
> write a hosts file, with machines referring to themselves, then copy the
> hosts file to another PC, and expect that "127.0.0.1 mywebserver" will
> connect to the webserver on the other PC.
>
>> Is there any issue if the real HOSTNAME is associated with some other
>> nonroutable address in /etc/hosts if (a) the machine is not connected
>> to a network
>
> Shouldn't be.  You can have any number of interfaces and addresses on a
> machine.  So long as, for itself, a name and IP are associated with each
> other in a useable manner when you try to use them.
>
> e.g. You might have a box with a hostname of "fred", it might have four
> network interfaces, it *might* have a hosts file like:
>
> 127.0.0.1 localhost fred
> 192.168.0.1 groundfloornet ground
> 192.168.1.1 firstfloornet first
> 192.168.2.1 secondfloornet second
> 192.168.3.1 thirdfloornet third
>
> It could refer to itself using any of those addresses.  It's when other
> machines want to connect to it that you have to be sure that they've got
> the information available to them.
>
>> or (b) if it is connected to a network but has some other IP (possibly
>> routable) address on that network--either where other machines on the
>> network know the machine name and IP (from DNS, e.g.) or where they
>> don't?
>
> The hosts file entries are for use within the machine itself, it can
> have all sorts of extra information, and not be a problem for other
> machines.  Unless you make the mistake of using non-unique names on more
> than one machine (if you had another "fred" box, elsewhere, your use of
> "fred" on this box would prevent it connecting with the other fred box,
> in a many circumstances).
>
> You can put aliases in your hosts file, that allow you to refer to some
> address by yet another name (like my five line example, above).  The box
> in the foyer might well be 192.168.0.12, hostname "wilma".  You could
> add an entry to it on your hosts file, calling it "dino", and when you
> refer to "dino", your computer will read its host file, find the IP
> associated with it, and connect to it.
>
> There's a proviso with that sort of thing:  virtual hosts with
> webservers.  Your request also includes the name of the host you're
> trying to connect to.  The Apache webserver can server different pages
> from the one server based on the name in the request.
>
>

-- 
 		Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs