Your message dated Sat, 18 Feb 2012 15:36:11 +0100 with message-id <[email protected]> and subject line Re: Bug#609851: summary has caused the Debian Bug report #609851, regarding incorrect variables used to set hostname in dhclient-script to be marked as done.
This means that you claim that the problem has been dealt with. If this is not the case it is now your responsibility to reopen the Bug report if necessary, and/or fix the problem forthwith. (NB: If you are a system administrator and have no idea what this message is talking about, this may indicate a serious mail system misconfiguration somewhere. Please contact [email protected] immediately.) -- 609851: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=609851 Debian Bug Tracking System Contact [email protected] with problems
--- Begin Message ---Package: isc-dhcp-client Version: 4.1.1-P1-15 The logic to set the hostname on boot when that hostname is supplied via dhcp is not working. Looking at the code in dhclient-script, it appears flawed. Testing reveals unexpected content in the variables. My environment: the dhcp server is sending 'option host-name' to send the hostname to the client. Examining /var/lib/dhcp/dhclient.eth0.leases shows that the hostname is present. The same environment successfully hands out a hostname when the system is booted with Lenny; it fails when the system is booted with Squeeze. Note that I removed /etc/hostname to force it to get the hostname from dhcp. The hostname is being handed out by a system running Debian Etch and dhcp3-server 3.0.4-13+etch2 The code that sets the hostname on lenny is as follows: /sbin/dhclient-script from dhcp3-client version 3.1.1-6+lenny4, lines 102 to 107 set_hostname() { local current_hostname=$(hostname) if [ -z "$current_hostname" -o "$current_hostname" = "(none)" ]; then hostname "$new_host_name" fi } The code that sets the hostname on squeeze is as follows: /sbin/dhclient-script from isc-dhcp-client version 4.1.1-P1-15, lines 155 to 158 if [ -n "$old_host_name" -a -n "$host_name" -a \ "$host_name" != "$old_host_name" ]; then hostname "$new_host_name" fi The first thing that I believe is a bug is that the if clause tests against $old_host_name and $host_name, but the hostname is set to $new_host_name. I put some print statements around this clause to show the contents of the three variables. On boot, $old_host_name is empty, $host_name is empty, and $new_host_name has the hostname given to the machine from dhcp. Since this if clause tests that both $old_host_name and $host_name are non-empty, the statement to set the hostname is not executed. If, after the system has booted, I run '/etc/init.d/networking restart', the contents of the variables are $old_host_name = the host name assigned by dhcp, $host_name is empty, and $new_host_name is the hostname assigned by dhcp. Since $host_name is empty, the statement to set the hostname is not executed. Note that even though $old_host_name contains the hostname given out by dhcp, the hosts' name (as shown by running 'hostname') is "(none)". $old_host_name seems to be incorrectly populated. I believe the previous behavior of setting current_hostname=$(hostname) and testing it against "(none)" will cause the system to behave as I expect. I don't understand why the previous hostname must have content in order for the new hostname to be set, and it seems as though testing $host_name instead of $new_host_name is a typo. Thank you, -ben
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--- Begin Message ---Version: 4.2.2-2 On Sun, Dec 4, 2011 at 00:00:06 +0100, Helmut Grohne wrote: > This is a summary for those attempting to squash rc bugs. > > As of 4.2.2-1 /sbin/dhclient-script implements a set_hostname function > that unconditionally updates the host name if request host-name is set > in /etc/dhcp/dhclient.conf which is the default. This means that in a > default setup of dhcp any dhcp server can change the hostname. It is > known that this break (among other things) X11. It also contradicts the > documentation (man dhcp-options) "This option is only honored by > dhclient-script(8) if the hostname for the client machine is not set." > That seems fixed (at least to some extent) in 4.2.2-2: if [ -z "$current_hostname" ] || [ "$current_hostname" = '(none)' ] || [ "$current_hostname" = 'localhost' ] || [ "$current_hostname" = "$old_host_name" ]; then if [ "$new_host_name" != "$old_host_name" ]; then hostname "$new_host_name" fi fi I.e. if the current host name doesn't match the previous one from dhcp then don't change it. Cheers, Julien
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