[SOLVED] ssh fails due to changed RSA fingerprint

[Pro-reason]

I have been happily using ssh to log on to another computer for some time.

Now, suddenly, it doesn't work. I tried to connect as usual, and I got a message saying that the fingerprint of the host had changed. I had to delete my ~/.ssh/known_hosts file.

If I now try to connect, it first asks me whether I trust the authenticity of the host. I say yes, and then it lets me enter the password. However, it always rejects the password.

I get the same thing if I go to the other computer and try to connect to my own.

Why has this happened?

[Sef]

moved to server platforms.

[cpetercarter]

The problem probably lies in the computer you are trying to log into. Perhaps the username or password has been changed, or the owner has changed the sshd configuration file to permit access only by certain users, or in some other way.

[Pro-reason]

The problem probably lies in the computer you are trying to log into. Perhaps the username or password has been changed, or the owner has changed the sshd configuration file to permit access only by certain users, or in some other way.

No, that's not it.

[jerome1232]

Generally if the RSA fingerprint changes and there's no reason for the server to have regenerated it's keys; Your not connecting to the machine you think you are.

I'm immediately suspicious of some sort of man in the middle attack.

I don't know how to go about finding out more though

[Pro-reason]

Our ADSL modem/router is connected to the internet, and provides a local network. Its local IP address is 10.1.1.1.

This computer is 10.1.1.2. The other computer is 10.1.1.3.

Each computer runs Hardy, and has one account on each. I know the passwords for both.

The command “ssh erin@10.1.1.3” used to work.

[cariboo]

Can you log on to the computer itself, that is if you've got a keyboard and monitor hooked up to it?

Jim

[Pro-reason]

Can you log on to the computer itself, that is if you've got a keyboard and monitor hooked up to it?

Jim

Of course.

[windependence]

Generally if the RSA fingerprint changes and there's no reason for the server to have regenerated it's keys; Your not connecting to the machine you think you are.

I'm immediately suspicious of some sort of man in the middle attack.

I don't know how to go about finding out more though

I'd think more like his IP is not static and when he logs in with the new DHCP address, ssh does not recognize the machine or associates it with another machine that was allocated that address at another time.

-Tim

[Pro-reason]

I'd think more like his IP is not static and when he logs in with the new DHCP address, ssh does not recognize the machine or associates it with another machine that was allocated that address at another time.

-Tim

The IP address that our ISP assigns us is dynamic, but on this side of the router the IP addresses are stable: 10.1.1.1, 10.1.1.2, and 10.1.1.3.

Would the external address make any difference?