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Re: [Raspbian-devel] change hostname & static IP & ???

The SD cards can in general be swapped around Raspberry PI cards.

The MAC address is stored in the network adapter on the Raspberry PI, so unless you change it, each raspberry PI will have a uniqe MAC address.

Default IP configuration is to use DHCP. This usually causes the the address to follow the raspberry PI card, since the router will remember which IP address it used to have, unless the card has been offline for some time. Some routers forgets this information on reboot. If the router does not have old information about the MAC address from the client, it can use the hint sent from the client before deciding which address it shall have. The client usually hints about which IP address it had last time it was connected. When moving SD cards between raspberry PI cards, this hint will follow the SD card, since it is stored in a file.

If you configure the IP address to be static, then the address will follow the SD card, since that is where you store that information:


On Tue, Apr 12, 2016 at 1:02 AM, ken <gebser@mousecar.com> wrote:
This is on Wheezy for a Raspberry Pi.

Using dd, I copied the SD card for one (nicely working and configured) system onto another SD card.  I want to use this second card for another system, so need to change the hostname and (static) IP address.  Yesterday I grepped the whole system for one and then the other and where I found either, I made appropriate changes (i.e., previous hostname to new hostname, previous IP address to new IP address).  I also zeroed out all text-based files in /var/log/ (e.g., >messages), just to start the new system with clean logs.

Both the previous (still running) system and the new one (not yet running) are to be on the same LAN, so I'm pretty certain that no other networking configuration-- like broadcast or netmask-- needs to be touched (how could it need any?).

Neither of these systems has any public-facing services currently running.

My concerns are these:

Only files which grep could find were amended. (Note that grep was run on the card when it was mounted on another system, not when the system on that card was booted and running.)  Is there a file of some kind, perhaps, which encodes either the hostname and/or IP address in such a way that would hide it/them from grep?

Since people are supposed to be able (I think, never done) to take an SD out of one RPi and put and boot it in another RPi (with the same hardware), I didn't make any attempt to find and change any hardware designations, like the MAC address of the NIC.  Is that okay?

Is there anything I'm missing or forgetting?

tia for fullohelp tips.

Stian Skjelstad
Barnfind Technologies

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