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Dulik: /* Linux Debian hostname a FQDN */

2011-02-19T15:32:45Z

Linux Debian hostname a FQDN

← Starší verze		Verze z 19. 2. 2011, 15:32
Řádek 14:		Řádek 14:
	one network and would then possibly have more than one FQDN.		one network and would then possibly have more than one FQDN.

	The FQDN of the system is the name that the resolver(3)		'''The FQDN of the system is the name that the resolver(3) returns for the host name.'''
	returns for the host name.

	The resolver is the code within libc that maps hostnames to IP		The resolver is the code within libc that maps hostnames to IP

Dulik: /* Co můj problém? */

2010-07-20T11:33:41Z

Co můj problém?

← Starší verze		Verze z 20. 7. 2010, 11:33
Řádek 89:		Řádek 89:
	backup.utb.cz. 86400 IN CNAME '''vega.utb.cz'''.		backup.utb.cz. 86400 IN CNAME '''vega.utb.cz'''.

	~~Jak prosté~~...		A řešení: dopsal jsem do /etc/hosts veřejnou IP adresu a jiné doménové jméno:

			127.0.0.1 localhost
			195.113.96.248 backup.fai.utb.cz backup

			Jak prosté?

Dulik: /* Co můj problém? */

2010-07-20T11:12:05Z

Co můj problém?

← Starší verze		Verze z 20. 7. 2010, 11:12
Řádek 74:		Řádek 74:

	=Co můj problém?=		=Co můj problém?=
	DNS na UTB mělo již pro stroj s názvem backup.utb.cz záznam:		Centrální DNS na UTB mělo již pro stroj s názvem backup.utb.cz záznam:
	backup:/proc# dig backup.utb.cz		backup:/proc# dig backup.utb.cz

Dulik v 20. 7. 2010, 11:11

2010-07-20T11:11:43Z

@@ Řádek 6: / Řádek 6: @@
 Poté, co jsem jeden stroj s Debian Lenny pojmenoval "backup", připojil na UTB k síti s DHCP a následně celé dopoledne řešil, proč si některé démony myslí, že s hostname je "vega" nebo "vega.utb.cz", podařilo se mi najít [http://linux.derkeiler.com/Mailing-Lists/Debian/2007-09/msg00017.html toto vysvětlení]:
+=Linux Debian hostname a FQDN=
 A host is a host. One box, one name.
@@ Řádek 22: / Řádek 22: @@
 With libc6 (or was it 5), the resolver is configured in /etc/nsswitch.conf. That's Name Service Switch, and has many options.
-===So what is the correct way of setting the hostname and the FQDN?===
+==So what is the correct way of setting the hostname and the FQDN?==
 Ok. So you've named the computer. You put this hostname (the name up
@@ Řádek 72: / Řádek 72: @@
 Doug.

Dulik v 20. 7. 2010, 11:04

2010-07-20T11:04:55Z

← Starší verze		Verze z 20. 7. 2010, 11:04
Řádek 1:		Řádek 1:
	Jak Linux Debian nastavuje hostname?		Jak Linux Debian nastavuje hostname, resp. FQDN (fully qualified domain name)?

	Myslíte, že hostname stačí napsat do /etc/hostname ?		Myslíte, že hostname stačí napsat do /etc/hostname ?

	Chyba lávky. Je to ~~mnohem~~ složitější.		Chyba lávky. Je to složitější.
	Poté, co jsem jeden stroj s Debian Lenny pojmenoval "backup", připojil k ~~UTB~~ síti s DHCP a následně celé dopoledne řešil, proč si některé démony myslí, že s hostname je "vega" nebo "vega.utb.cz", podařilo se mi najít [http://linux.derkeiler.com/Mailing-Lists/Debian/2007-09/msg00017.html toto vysvětlení]:
			Poté, co jsem jeden stroj s Debian Lenny pojmenoval "backup", připojil na UTB k síti s DHCP a následně celé dopoledne řešil, proč si některé démony myslí, že s hostname je "vega" nebo "vega.utb.cz", podařilo se mi najít [http://linux.derkeiler.com/Mailing-Lists/Debian/2007-09/msg00017.html toto vysvětlení]:

	A host is a host. One box, one name.		A host is a host. One box, one name.
Řádek 21:		Řádek 22:
	With libc6 (or was it 5), the resolver is configured in /etc/nsswitch.conf. That's Name Service Switch, and has many options.		With libc6 (or was it 5), the resolver is configured in /etc/nsswitch.conf. That's Name Service Switch, and has many options.

	~~'''~~So what is the correct way of setting the hostname and the FQDN?~~'''~~		===So what is the correct way of setting the hostname and the FQDN?===

	Ok. So you've named the computer. You put this hostname (the name up		Ok. So you've named the computer. You put this hostname (the name up

Dulik v 20. 7. 2010, 11:03

2010-07-20T11:03:09Z

← Starší verze		Verze z 20. 7. 2010, 11:03
Řádek 21:		Řádek 21:
	With libc6 (or was it 5), the resolver is configured in /etc/nsswitch.conf. That's Name Service Switch, and has many options.		With libc6 (or was it 5), the resolver is configured in /etc/nsswitch.conf. That's Name Service Switch, and has many options.

	So what is the correct way of setting the hostname and the FQDN?		'''So what is the correct way of setting the hostname and the FQDN?'''

	Ok. So you've named the computer. You put this hostname (the name up		Ok. So you've named the computer. You put this hostname (the name up
Řádek 27:		Řádek 27:
	in /etc/hostname.		in /etc/hostname.

	So now /bin/hostname will give you your hostname. How does hostname -f		So now /bin/hostname will give you your hostname. How does
			hostname -f
	give the FQDN?		give the FQDN?

Dulik v 20. 7. 2010, 11:02

2010-07-20T11:02:05Z

← Starší verze		Verze z 20. 7. 2010, 11:02
Řádek 38:		Řádek 38:
	So, the first place it will look is in /etc/hosts. It will see, e.g.		So, the first place it will look is in /etc/hosts. It will see, e.g.

	192.168.1.5 rocky.hooton rocky		192.168.1.5 rocky.hooton rocky

	It will see a FQDN and return rocky.hooton to my hostname -f request.		It will see a FQDN and return rocky.hooton to my hostname -f request.
Řádek 45:		Řádek 45:
	line was:		line was:

	127.0.0.1 localhost		127.0.0.1 localhost

	?		?
Řádek 51:		Řádek 51:
	It would then look in /etc/resolve.conf and see:		It would then look in /etc/resolve.conf and see:

	nameserver 192.168.1.1		nameserver 192.168.1.1

	It will then issue a DNS request to 192.168.1.1 asking what the FQDN is		It will then issue a DNS request to 192.168.1.1 asking what the FQDN is

Dulik: Nová stránka: Jak Linux Debian nastavuje hostname? Myslíte, že hostname stačí napsat do /etc/hostname ? Chyba lávky. Je to mnohem složitější. Poté, co jsem jeden stroj s Debian Lenny p...

2010-07-20T11:01:27Z

Nová stránka: Jak Linux Debian nastavuje hostname? Myslíte, že hostname stačí napsat do /etc/hostname ? Chyba lávky. Je to mnohem složitější. Poté, co jsem jeden stroj s Debian Lenny p...

Nová stránka

Jak Linux Debian nastavuje hostname?

Myslíte, že hostname stačí napsat do /etc/hostname ?

Chyba lávky. Je to mnohem složitější.
Poté, co jsem jeden stroj s Debian Lenny pojmenoval "backup", připojil k UTB síti s DHCP a následně celé dopoledne řešil, proč si některé démony myslí, že s hostname je "vega" nebo "vega.utb.cz", podařilo se mi najít [http://linux.derkeiler.com/Mailing-Lists/Debian/2007-09/msg00017.html toto vysvětlení]:

A host is a host. One box, one name.

A network is a network. One network, one name.

Most hosts are only on one network, however, some hosts are on more than
one network and would then possibly have more than one FQDN.

The FQDN of the system is the name that the resolver(3)
returns for the host name.

The resolver is the code within libc that maps hostnames to IP
addresses.

With libc6 (or was it 5), the resolver is configured in /etc/nsswitch.conf. That's Name Service Switch, and has many options.

So what is the correct way of setting the hostname and the FQDN?

Ok. So you've named the computer. You put this hostname (the name up
to but not including the network name(s) to which the box is attached),
in /etc/hostname.

So now /bin/hostname will give you your hostname. How does hostname -f
give the FQDN?

It asks the resover what the dommain name is. The resolver consults the
/etc/nsswitch.conf file so see where to look. On debian, it tells it
that for hosts it should consult files and if it doesn't get an answer,
to consult the DNS via a DNS query to the nameserver that is configured
with files, in this case /etc/resolv.conf.

So, the first place it will look is in /etc/hosts. It will see, e.g.

192.168.1.5 rocky.hooton rocky

It will see a FQDN and return rocky.hooton to my hostname -f request.

Now, what if you didn't have this host in /etc/hosts? What if the only
line was:

127.0.0.1 localhost

?

It would then look in /etc/resolve.conf and see:

nameserver 192.168.1.1

It will then issue a DNS request to 192.168.1.1 asking what the FQDN is
for rocky.

It will be told rocky.hooton.

---

So to finally answer your question, you configure your FQDN wherever you
want names resovled. If you want it in files on the box itself, then it
goes in /etc/hosts. If you run your own name server like I do (I run
dnsmasq for simplicity) then you only have to record the information in
one place.

I hope this long-winded answer is of some help. For more clarity, I'd
suggest __UNIX_System_Administration_Handbook__ by Evi Nemeth, et. al.

Doug.