I want to change the password for line con, line vty and enable secret, I have 2600 devices. how I can do that easily. is that safe to do all at one or chunk of devices at the time.
You can use Netconfig to do this. There are templates to help you with this. I would not just due all 2600 at once. Start with a small group (like 10) to make sure it works as expected. Once you're confident in the results, then schedule the job for the rest of the devices.