Settings of /etc/hosts and /etc/hostname

[satimis]

Hi folks,

Ubuntu 10.10 64 bit


I need to set /etc/hostname and /etc/hosts so that on running;

$ hostname

ub1004

$ hostname -a

ub1004

I set them as;

cat /etc/hostname

ub1004

cat /etc/hosts

127.0.0.1	localhost.localdomain
123.123.123.123	ub1004.domain.com	ub1004

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

After reboot:

cat /etc/hostname

ub1004

$ cat /etc/hosts

127.0.0.1	ub1004	localhost.localdomain	localhost
::1	ub1004	localhost6.localdomain6	localhost6
#127.0.1.1	ub1004
123.123.123.123	ub1004.domain.com	ub1004

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

On running

$ hostname

ub1004

$ hostname -a

localhost.localdomain localhost localhost6.localdomain6 localhost6 ub1004 ub1004.domain.com

Please advice.

TIA


B.R.
satimis

[ptkobe]

I'm guessing your question is why is the hosts file changing after reboot.

I'll bet on some administrative routine that runs during the boot ip request or network authentication.
Are you in charge of those processes? If they exist, that is.

Of course, if you are not your machine's administrator, it may be a local routine. But as you are editing hosts...

Is any of that possible?

Regards
Luis

[satimis]

I'm guessing your question is why is the hosts file changing after reboot.

I'll bet on some administrative routine that runs during the boot ip request or network authentication.
Are you in charge of those processes? If they exist, that is.

Of course, if you are not your machine's administrator, it may be a local routine. But as you are editing hosts...

Is any of that possible?

Regards
Luis

Hi Luis,

I'm the admin. This is a virtual machine running Oracle VBox as virtualizer. I just discovered this strange happening /etc/hosts changed after reboot.

host - Ubuntu 1010 64 bit
VMs - Ubuntu 1004/1010 Debian 6.0, all 64 bits, Windows 32/64 bits etc.

Only Ubuntu has this problem.

On Debian:-
> hostname
> hostname -a
display the same output, same hostname "deb600dk01"

> cat /etc/hosts

127.0.0.1		localhost
123.123.123.123. 	deb600dk01.domain.com	deb600dk01

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

/etc/hosts won't change after reboot.

I edited /etc/hosts of Ubuntu similar to that of Debian. But it doesn't work. Problem still remains.

B.R.
satimis

[elija]

It could be DHCP rewriting it

[satimis]

It could be DHCP rewriting it

Hi,

All Ubuntu and Debian VMs and host are running fixed IP NOT DHCP

$ cat /etc/network/interfaces

auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet manual

auto br0
iface br0 inet static
        address xxx.xxx.xxx.xxx
        network xxx.xxx.xxx.xxx
        netmask 255.255.255.0
        broadcast xxx.xxx.xxx.xxx
        gateway xxx.xxx.xxx.xxx
        bridge_ports eth0
        bridge_fd 9
        bridge_hello 2
        bridge_maxage 12
        bridge_stp off

B.R.
satimis

[ptkobe]

Hi, satimis. Ok.
First, what are the changes? They redirect your local machine name ip4 lookup searches to the loopback, and adds a line doing the same for the IP6 searches (missing the already existent line below).
That's not bad. Can you live with it?

Second, if not, or if you really want to try to get to the bottom of it, I'll check the boot scripts (/etc/rc2.d/S*) and the /etc/init/* boot scripts, and also the /etc/rc.local file to try to find some code that may be responsible for it.

I never used VBox, I use kvm/libvirt, but I'm pretty sure that boot changes of /etc/hosts is not a "normal" thing. Maybe someone else may know more.

Please don't mind me telling the following, we both probably been around on computers for a while.
Check the dates on the above mentioned scripts with ls -lt. You may have made some change on them you have forgotten

Regards
Luis

PS: From $ man hostname
-a, --alias
Display the alias name of the host (if used). This option is deprecated and should not be used anymore.
??

[ptkobe]

Also, if you are using
# The primary network interface
auto eth0
iface eth0 inet manual

you may also check the /etc/network/if-*.d scipts

$ man interfaces
The manual Method
This method may be used to define interfaces for which no configuration is done by default. Such interfaces can be configured
manually by means of up and down commands or /etc/network/if-*.d scripts.

I have a similar conf (with libvirt) and I don't have to use that. The
bridge_ports eth0
line is enough for me.

You may try to comment those lines as an easy way to discard /etc/network/if-*.d scripts from being messing with your /etc/hosts file.

[satimis]

Also, if you are using
# The primary network interface
auto eth0
iface eth0 inet manual

you may also check the /etc/network/if-*.d scipts

$ man interfaces
The manual Method
This method may be used to define interfaces for which no configuration is done by default. Such interfaces can be configured
manually by means of up and down commands or /etc/network/if-*.d scripts.

I have a similar conf (with libvirt) and I don't have to use that. The
bridge_ports eth0
line is enough for me.

You may try to comment those lines as an easy way to discard /etc/network/if-*.d scripts from being messing with your /etc/hosts file.

Hi Luis,

Up to now I haven't discovered this change causing problem in operation. I just wonder why all Ubuntu OS here both host and VMs have this problem. Debian VMs don't suffer this problem.

Following is host data (Ubuntu 10.10 desktop 64bit):-

$ cat /etc/hosts

127.0.0.1	ub1004	localhost.localdomain	localhost
::1	ub1004	localhost6.localdomain6	localhost6
#127.0.1.1	ub1004
192.xxx.xxx.xxx	ub1004.domain.com	ub1004

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

$ cat /etc/hosts

127.0.0.1	ub1004	localhost.localdomain	localhost
::1	ub1004	localhost6.localdomain6	localhost6
#127.0.1.1	ub1004
192.xxx.xxx.xxx	ub1004.domain.com	ub1004

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

$ cat /etc/network/interfaces

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet manual

auto br0
iface br0 inet static
	address	192.xxx.xxx.xxx
	network 192.xxx.xxx.xxx
	netmask	255.255.255.0
	broadcast 192.xxx.xxx.xxx
	gateway	192.xxx.xxx.xxx
	bridge_ports eth0
	bridge_fd 9
	bridge_hello 2
	bridge_maxage 12
	bridge_stp off

$ cat /etc/udev/rules.d/70-persistent-net.rules

# This file maintains persistent names for network interfaces.
# See udev(7) for syntax.
#
# Entries are automatically added by the 75-persistent-net-generator.rules
# file; however you are also free to add your own entries.

# PCI device 0x1969:0x1026 (ATL1E)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:26:18:44:b6:1a", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"

B.R.
satimis