It seems the certificate-based login doesn't work on both sides of the remote connection when using scp? Scenario: User on PC A can SSH login to PCs B and C with his certificate, no password prompt. When User on PC A runs a scp operation from B to C he's asked for the password on C.
Does the scp actually open a connection from B to C (User doesn't have a certificate on B)? This would explain the problem. I hoped to avoid such a problem by scping from a third machine that normally has certificate-based access to all machines.
Kai