Changing hostid under Solaris 8

Sometimes you may need to change a machine's hostid or MAC address temporarily (for example, due to a hardware failure of a machine where a licensed product is installed).

To change the hostid, usually it's sufficient (and very easy) to use the hid ( or hid2 ) programs, which change the hostid of the running kernel. See the excellent Sun NVRAM/hostid FAQ at http://www.squirrel.com for more details.

However hid2 doesn't seem to work on Solaris 8, and anyway sometimes the licensing software (Veritas Volume Manager is one example) actually makes a call to see the contents of the PROM, rather than looking at the hostid in the kernel, so you will need to modify the hostid in the PROM.

1. Download the hid_solaris2 binary from http://yenigul.net/change_hostid. If you want to compile the code yourself you can download it from http://yenigul.net/change_hostid/hid-1.7.4.tar.gz.
2. Save the original hostid to somewhere:

   # hostid > /etc/hostid_orig

3. Set permissions on the hid_solaris2 (assuming the binary is under /var/tmp)

   # chmod 0755 /var/tmp/hid_solaris2

4. To set the new hostid (i.e: 84abe39d) issue the following command:

   # /var/tmp/hid_solaris2 84abe39d | sh
   
   physmem 2e694
   hw_serial: 0x32323130 = 0x32323235
   hw_serial+4: 0x39313931 = 0x38353734
   hw_serial+8: 0x36390000 = 0x33370000
   

5. The new hostid will be active until next reboot. To make the change persistent across reboots create a solaris startup scripts.