Re: Hostname

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Date: Thu, 23 Sep 2004 02:27:43 -0400

Alexander Dalloz wrote:
> On Sun, 01 Aug 2004 17:07:53 -0500 George wrote:
>
>
>>>>I'm so glad that you're so thoroughly and perfectly knowledgable
>>>>about every single American ISP that you can pontificate like this.
>>>>
>>>>Geo
>>>
>>>Got your irony. Though it is a network scripts function of at least
>>>Redhat / Fedora and nothing the ISP does.
>>>
>>>Alexander
>>
>>Wrong again! Some American ISPs do things a little differently from the
>>norm, and that can effect Fedora. After I got the help from a mailinglist
>>user and changed my machine name, I called Comcast about it and they said
>>Yes, what I described as my problem does happen. In my case the main
>>reason had something to do with setup for IE, so said Comcast. It wasn't
>>irony, it was sarcasm.
>>
>>G
>
>
>
> I don't judge the reasons ISP have for passing specific DHCP information.
> But the issue with localhost as hostname is a Fedora side thing. You are
> wrong if you think that it depends on the ISP. If you only believe your
> eyes and not my words I suggest you investige the network setup scripts
> your own. Maybe start at line 202 in
> /etc/sysconfig/network-scripts/network-functions and chech it's call in
> /etc/sysconfig/network-scripts/ifup and
> /etc/sysconfig/network-scripts/ifup-post. If you think yourself a bit
> about the backgrounds, I suspect you will quickly understand that a
> hostname localhost for a networked host is not valid.
>
> Alexander
>
>

Since the original post asked for the "intricacies" here's a little more
mind numbing detail. At after init starts rc.sysinit checks for a
hostname. If it gets nothing back (I guess this would be always) it
sets it to localhost. Later the init.d/network script runs
sysconfig/ifup for each sysconfig/network-scripts/ifcfg-ethX. X
starting at 0 in most cases.

The end of the ifup script execs ifup-post. ifup-post checks to see if
a hostname is needed. (Look for the call to need_hostname.)
need_hostname returns true if the hostname is null or "localhost".
ifup-post then gets the hostname by calling ipcalc.

One side effect of this is that the first ethernet card sets the
hostname. For the second card, ifup-post calls need_hostname which
returns false because the a "valid" hostname was set by the first card.
  Of course if you don't like the way it works you can always change it.

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