OCI: Instance 20 Second Delay After Bad Password Login Attempt in SSH

Applies to

Oracle Cloud Infrastructure - Version N/A and later

Linux x86-64

Symptoms

When a wrong password is used when logging into an instance using SSH password authentication, there is a delay of 20 seconds before the next password prompt is displayed.

Cause

The /etc/pam.d/system-auth or /etc/pam.d/password-auth files include entries for LDAP/AD 

authentication in addition to local user authentication.

Example:
auth        required      pam_env.so
auth        required      pam_tally2.so deny=3 unlock_time=2
auth        sufficient    pam_unix.so nullok try_first_pass
auth        sufficient    pam_krb5.so try_first_pass realm=<LDAP-DOMAIN1>
auth        sufficient    pam_krb5.so try_first_pass realm=<LDAP-DOMAIN2>
auth        requisite     pam_succeed_if.so uid >= 500 quiet_success
auth        required      pam_deny.so