Attachment 249229 Details for Bug 440809

Detailed notes showing the output of various commands re 'hostname'.

TroubleshootingHostname-11.1-Beta3-KDE4-i386 (text/plain), 9.37 KB, created by Geoff Farrell on 2008-11-01 05:35:44 UTC

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Creator: Geoff Farrell

Created: 2008-11-01 05:35:44 UTC

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>Troubleshooting openSUSE 11.1-Beta3-KDE4-i386 hostname:
>
>Can't change hostname with the 'hostname' command.
>
>Problem: hostname 'linux' persists despite attempts to rename it to something else.
>
>---------------------------------------------------------------------------------------
>Summary:
>
>When trying to change the hostname, it is not changed in all places that rely on definition of the hostname for system purposes. Changing it in YaST Network Services succeeds in changing /etc/HOSTNAME and the 127.0.0.2 entry in /etc/hosts, but not for the first field of the 127.0.0.1 entry, nor for the 'hostname' line in /etc/NetworkManager/nm-system-settings.conf. Changing it with the 'hostname' command results in changes to /etc/HOSTNAME, but not to /etc/hosts or etc/NetworkManager/nm-system-settings.conf.
>
>The result is confusion within the system, where attempts to see what hostname is set will produce different results. For example, the 'hostname' command will show what it has been changed to ('MyHost.MyNetwork', say), as will the contents of /etc/HOSTNAME, but starting a console will show the prompt as 'user@linux:~>'. Any changes made are reset by rebooting the machine, whereupon the hostname 'linux' is resurrected. That is, the output of the hostname command is 'linux', even though the contents of /etc/HOSTNAME is still 'MyHost.MyNetwork'.
>
>It seems that NetworkManager's use of a hostname in the nm-system-settings.conf file is new, as is the format of the 127.0.0.1 line in /etc/hosts, but these two changes have not been coordinated well. To fix this hostname problem, one of two courses of action could be taken, followed by a third:
>
>a. If NetworkManager is to rely on its own config file for the hostname setting, then:
>(1) the 'hostname' command should be modified to alter the /etc/NetworkManager/nm-system-settings.conf file, as well as the /etc/HOSTNAME file; and
>(2) YaST Network Settings should save its 'hostname' setting to the /etc/NetworkManager/nm-system-settings.conf file, as well as the first hostname field of the 127.0.0.1 entry in /etc/hosts.
>
>*Or*
>
>b. NetworkManager could just refer to /etc/HOSTNAME, which exists precisely for the purpose of defining just that! YaST Network Settings would still need to save its 'hostname' setting to the first hostname field of the 127.0.0.1 entry in /etc/hosts.
>
>c. In addition to 'a' or 'b' above, maybe the 'hostname' command could also be modified to change the first hostname field of the 127.0.0.1 entry in /etc/hosts.
>
>This is for an installation on a hard drive partition from openSUSE-11.1-Beta3-KDE4-LiveCD-i386.iso; network is set up using NetworkManager, not ifup.
>---------------------------------------------------------------------------------------
>
>Detailed notes:
>
>1. After installation, /etc/hosts has two entries for 127.0.0.1:
>
>  127.0.0.1		linux		localhost.localdomain localhost
>
>  127.0.0.1		localhost
>
>2. /etc/hosts also has entry for 127.0.0.2:
>
>  127.0.0.2		linux-rl8w.site	linux-rl8w
>
>3. Ping of 127.0.0.1 produces normal result, but 2 x entries looks wrong.
>
>4. cat /etc/HOSTNAME produces:
>
>  linux-rl8w.site
>
>Shows an identity crisis: is the hostname 'linux' or 'linux-rl8w'?
>
>5. Konsole prompt shows:
>
>  geoff@linux:~>
>
>suggesting that it thinks the hostname is 'linux'.
>
>6. Set hostname in YaST2-> Network Devices-> Network Settings:
>
>  Hostname:		MyHost
>  Domain:		MyNetwork
>  Change Hostname via DHCP: Unchecked
>  Write Hostname to /etc/hosts:	Checked
>  Domain Search:	MyNetwork
>
>The 127.0.0.2 entry in /etc/hosts then changed to:
>
>  127.0.0.2		MyHost.MyNetwork	MyHost
>
>but 2 x 127.0.0.1 entries remained, unchanged.
>
>7. cat /etc/HOSTNAME now produces:
>
>  geoff@linux:~> cat /etc/HOSTNAME
>  MyHost.MyNetwork
>
>but note that Konsole prompt still shows 'geoff@linux'.
>
>8. Output of 'hostname' command:
>
>  geoff@linux:~> hostname
>  linux
>
>9. Changing hostname with the 'hostname' command:
>
>  linux:~ # hostname MyHost.MyNetwork
>  linux:~ # hostname
>  MyHost.MyNetwork
>
>10. Close Konsole, reopen; prompt shows hostname change:
>
>  geoff@MyHost:~>
>
>11. Log out as user; log back in. Start Konsole. Prompt still shows new hostname:
>
>  geoff@MyHost:~>
>
>12. Re-boot, log in, Start Konsole. Prompt shows:
>
>  geoff@linux:~>
>
>13. Output of hostname command:
>
>  geoff@linux:~> hostname
>  linux
>
>14. Output of cat /etc/HOSTNAME:
>
>  geoff@linux:~> cat /etc/HOSTNAME
>  MyHost.MyNetwork
>
>15. /etc/hosts is unchanged - ie, 2 x 127.0.0.1 addresses, and 127.0.0.2 with the 'MyHost.MyNetwork' entry. It seems the persistent 'linux' name is coming from the first 127.0.0.1 entry.
>
>16. More 'hostname' commands:
>
>  geoff@linux:~> hostname -f
>  linux
>
>  geoff@linux:~> hostname -a
>  localhost.localdomain localhost
>  
>  geoff@linux:~> hostname -s
>  linux
>  
>17. Trying manual amendment of /etc/hosts to have only *one* entry of 127.0.0.1, defined as:
>
>  127.0.0.1 localhost.localdomain	localhost
>
>ie, conventional. Also changed 4 x blank lines after 127.0.0.2 entry to only one. Ran rcnetwork restart.
>
>  linux:~ # vi /etc/hosts
>
>  linux:~ # rcnetwork restart
>  Shutting down the NetworkManager                                                                                                                            done
>  Shutting down network interfaces:
>		eth0      device: nVidia Corporation CK804 Ethernet Controller (rev a3)                                                                                 done
>  Shutting down service network  .  .  .  .  .  .  .  .  .                                                                                                    done
>  Starting the NetworkManager                                                                                                                                 done
>
>18. 'linux' hostname is still persistent:
>
>  linux:~ # hostname
>  linux
>
>but at least /etc/hosts has retained the conventional 127.0.0.1 entry:
>
>  linux:~ # cat /etc/hosts
>  #
>  # hosts         This file describes a number of hostname-to-address
>  #               mappings for the TCP/IP subsystem.  It is mostly
>  #               used at boot time, when no name servers are running.
>  #               On small systems, this file can be used instead of a
>  #               "named" name server.
>  # Syntax:
>  #
>  # IP-Address  Full-Qualified-Hostname  Short-Hostname
>  #
>  127.0.0.1       localhost.localdomain   localhost
>
>  # special IPv6 addresses
>  ::1             localhost ipv6-localhost ipv6-loopback
>
>  fe00::0         ipv6-localnet
>
>  ff00::0         ipv6-mcastprefix
>  ff02::1         ipv6-allnodes
>  ff02::2         ipv6-allrouters
>  ff02::3         ipv6-allhosts
>
>  127.0.0.2       MyHost.MyNetwork MyHost
>
>19. Re-booting. Konsole prompt after login:
>
>  geoff@linux:~>
>
>20. Output of hostname command:
>
>  geoff@linux:~> hostname
>  linux
>
>21. cat /etc/hosts shows that 127.0.0.1 has a single entry, but it has reverted to:
>
>  127.0.0.1       linux   localhost.localdomain   localhost
>
>ie, 'linux' has returned, in the first hostname field. This proves that re-starting the network doesn't change the hostname setting, but that re-booting the computer does.
>
>22. Found 'linux' in /etc/NetworkManager/nm-system-settings.conf:
>
>  [main]
>  plugins=keyfile
>
>  [keyfile]
>  hostname=linux
>
>  [suse]
>  hostname-merged=true
>
>23. Changed 'hostname=linux' line to 'hostname=MyHost'. Re-booted. Hostname is now reported correctly. Prompt at Konsole start:
>
>  geoff@MyHost:~>
>
>24. Output of 'hostname' command:
>
>  geoff@MyHost:~> hostname
>  MyHost
>
>25. Contents of /etc/HOSTNAME:
>
>  geoff@MyHost:~> cat /etc/HOSTNAME
>  MyHost.MyNetwork
>
>26. Contents of /etc/hosts:
>
>  geoff@MyHost:~> cat /etc/hosts
>  #
>  # hosts         This file describes a number of hostname-to-address
>  #               mappings for the TCP/IP subsystem.  It is mostly
>  #               used at boot time, when no name servers are running.
>  #               On small systems, this file can be used instead of a
>  #               "named" name server.
>  # Syntax:
>  #
>  # IP-Address  Full-Qualified-Hostname  Short-Hostname
>  #
>  127.0.0.1       MyHost     localhost.localdomain   localhost
>
>  # special IPv6 addresses
>  ::1             localhost ipv6-localhost ipv6-loopback
>
>  fe00::0         ipv6-localnet
>
>  ff00::0         ipv6-mcastprefix
>  ff02::1         ipv6-allnodes
>  ff02::2         ipv6-allrouters
>  ff02::3         ipv6-allhosts
>
>  127.0.0.2       MyHost.MyNetwork MyHost
>
>27. Desired hostname of 'MyHost' is now persistent.
>
>28. It seems that NetworkManager's use of a hostname in the nm-system-settings.conf file is new, as is the format of the 127.0.0.1 line in /etc/hosts, but these two changes have not been coordinated well. 
>
>29. To fix this hostname problem, one of two courses of action could be taken, followed by a third:
>
>a. If NetworkManager is to rely on its own config file for the hostname setting, then:
>(1) the 'hostname' command should be modified to alter the /etc/NetworkManager/nm-system-settings.conf file, as well as the /etc/HOSTNAME file; and
>(2) YaST Network Settings should save its 'hostname' setting to the /etc/NetworkManager/nm-system-settings.conf file, as well as the first hostname field of the 127.0.0.1 entry in /etc/hosts.
>
>*Or*
>
>b. NetworkManager could just refer to /etc/HOSTNAME, which exists precisely for the purpose of defining just that! YaST Network Settings would still need to save its 'hostname' setting to the first hostname field of the 127.0.0.1 entry in /etc/hosts.
>
>c. In addition to 'a' or 'b' above, maybe the 'hostname' command could also be modified to change the first hostname field of the 127.0.0.1 entry in /etc/hosts.

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Attachments on bug 440809: 249229 | 254526 | 256370