Set hostname with FQDN

[DJ Lucas]

Following on from #2364, /etc/sysconfig/network should contain a fully qualified domain name now that /bin/hostname supports it...that is assuming that it correctly sets domainname and hostname in /proc/sys/kernel. I also notice that a few old switches (-h, --host, and --domainname), as well as the DECnet support, have been removed in comparison to the really old one from net-tools. Be on the lookout for scripts that test only for -f and then use switches that might not exist.

[DJ Lucas]

Not that it really matters much, but this ticket probably belongs to book, being that the /etc/sysconfig/network file is created in the book's instructions. If the new hostanme works correctly, which I haven't tested it yet, it shouldn't require a change to the localnet script.

[Matthew Burgess]

Not quite sure what your testcase would be, DJ, but this works for me:

$ ./hostname kyoto.internal.net
$ hostname
kyoto.internal.net
$

[DJ Lucas]

hostname -f &&
hostname -s &&
hostname -d

or

cat /proc/sys/kernel/hostname &&
cat /proc/sys/kernel/domainname

[bdubbs@…]

I don't think that's it Matt. What is wanted is something like:

bdubbs@lfs6:~$ hostname
lfs6
bdubbs@lfs6:~$ hostname --fqdn
lfs6.gdc.com

Using net-tools 1.60 / hostname 1.100 (2001-04-14).

This is set in /etc/rc.d/init.d/localnet:

hostname ${HOSTNAME} where HOSTNAME is defined in /etc/sysconfig/network as HOSTNAME=lfs6. The fqdn is picked up from /etc/hosts:

192.168.0.75 lfs6.gdc.com lfs6

From the man page:

THE FQDN

You can't change the FQDN (as returned by hostname --fqdn)

or the DNS domain name (asreturned by dnsdomainname) with this command. The FQDN of the system is the name that the resolver(3) returns for the host name.

Technically: The FQDN is the name gethostbyname(2) returns

for the host name returned by gethostname(2). The DNS domain name is the part after the first dot.

Therefore it depends on the configuration (usually in

/etc/host.conf) how you can change it. Usually (if the hosts file is parsed before DNS or NIS) you can change it in /etc/hosts.

[Matthew Burgess]

Replying to dj@…:

hostname -f &&
hostname -s &&
hostname -d

# hostname kyoto.internal.net
# hostname
kyoto.internal.net
# hostname -f
kyoto.internal.net
# hostname -s
kyoto
# hostname -d
internal.net

or

cat /proc/sys/kernel/hostname &&
cat /proc/sys/kernel/domainname

# cat /proc/sys/kernel/hostname
kyoto.internal.net
# cat /proc/sys/kernel/domainname
(none)

I'm testing in a limited environment though. This is not DNSed/DHCPed, so someone will have to test under those conditions I guess.

[DJ Lucas]

It's been a while, I don't have net-tools version installed, but I had thought that it correctly separated domainname and hostname if you supplied an fqdn when setting it. Maybe my memory is wrong. I've been using a script to modify proc directly for a long time. Bruce, you have it installed, does net-tools hostname set both hostname and domainname in proc correctly if passed a fqdn without arguments? If so, then we should probably bug inetutils maintainer (with a patch). I'll try and look at it a little later on this week. Matt, can you use -f when setting hostname and see if domainname is set correctly?

[DJ Lucas]

Eww yuck. I feel as thought I've been caught with my pants around my ankles. I am very sorry for the wild goose chase. I'm seeing lots of documentation on this, and almost all neglects to mention NIS. Apparently when I learned of it years ago, I had used one of these crappy documentation sources. Official documentation states that hostname and domainname (as used in /proc/sys/kernel) are NIS/YP hosntname and domainname, not DNS hostname and domainname.

from Documentation/sysctl/kernel.txt:

domainname & hostname:

These files can be used to set the NIS/YP domainname and the
hostname of your box in exactly the same way as the commands
domainname and hostname, i.e.:
# echo "darkstar" > /proc/sys/kernel/hostname
# echo "mydomain" > /proc/sys/kernel/domainname
has the same effect as
# hostname "darkstar"
# domainname "mydomain"

Note, however, that the classic darkstar.frop.org has the
hostname "darkstar" and DNS (Internet Domain Name Server)
domainname "frop.org", not to be confused with the NIS (Network
Information Service) or YP (Yellow Pages) domainname. These two
domain names are in general different. For a detailed discussion
see the hostname(1) man page.

Though most configurations would probably use DNS==NIS for domain name now days, aking that assumption on the user's behalf would not be the right thing to do.

Closing ticket invalid.

[Matthew Burgess]

DJ, I realise you've closed this now, and I'm not qualified enough to reopen it as my knowledge of NIS/YP is non-existent. However, note the following does what I, naive as I am to networking configuration, would expect:

# hostname -f kyoto.internal.net
# hostname
kyoto
# hostname -f
kyoto.internal.net
# hostname -s
kyoto
# hostname -d
internal.net
# cat /proc/sys/kernel/hostname
kyoto
# cat /proc/sys/kernel/domainname
(none)

[DJ Lucas]

Yes, and it should. My understanding of /proc/sys/kernel/domainname was completely off base. From Bruce's description, I'm making a partially educated (now) guess here, but ISTM that everything after the first dot should be discarded when setting with the -f flag. The domain name should be determined by consulting /etc/hosts, and should that fail, then by DNS (unless you've modified /etc/nsswitch.conf). I'm still going off of the man page for net-tools hostname, but if the new version holds true to the previous functions, setting only the short hostname (hostname kyoto) *should* return identical results.