Couldn't open /dev/null Error (Linux)
1. When using any command or application (such as ssh or scp) that writes to /dev/null the following error could occur:
Couldn't open /dev/null
2. When attempting to ssh the following error is given, even when SSHing to localhost:
Host key verification failed.
When running ssh -vvv user@localhost the exact debug line relating to this issue is: debug1: read_passphrase: can't open /dev/tty: Permission denied.
The permissions for the /dev/null device/special file do not allow writing to it.
Alter the permissions using chmod, as root:
chmod a+rw /dev/tty