cannot ssh to a cloned machine, while can to the original

Question

I have several Computer On module boards which are the same generation/version/model. I have setup the first in the series, with all configurations and settings I wanted.

I then took the Compact flash, and plugged it into a second board of the same type, hoping to be able to ssh to it same as I was able to do while plugged on the first.

However, I get connection refused error.

Note:

• both machines have the same IP, yet I do not plug them both at the same time
• I did arp -d x.y.z.a for the address between machines switching
• grep -ir ssh /var/log/* showing nothing
• I did removed /etc/udev/rules.d/70-persistent-net.rules between systems restarts
• If I take the CF and plugged it back to the first board, ssh is back.
• ping to the second board showed the IP address is set correctly

Does anyone have an idea where else shall I look for?

Answer 1

I guess your machine is refusing the connection, not the host. This is likely due to offending ssh key in your ~/.ssh/known_hosts file (1st machine key is different from 2nd machine one). You can remove the file, remove the offending key only or ignore the file in ssh config file if you will "swap" the machines frequently between original and cloned.

Answer 2

If you connect through a switch it may keep its own arp cache, which is mudding things up. Try to connect directly (cable only) to the 2nd box.

Another idea would be to run tcpdump on the box when you try to connect to it (assuming you can get inside via serial console) and see if it receives any packets.

And possibly the simplest explanation: some distributions bind IP address to MAC of NIC. If you changed hardware, you might have lost your network configuration. Can you ping the destination system?