Information
A Minimum Session Time should be set to at least 20 seconds.
Rationale:
Remote administration protocols like Telnet and SSH are commonly targeted by Brute Force or Dictionary attacks where a malicious user attempts to guess a valid username/password combination in order to gain control of the router. To slow down the rate at which an attacker can attempt to guess passwords Juniper routers can enforce a minimum session time, preventing an attacker from attempting to circumvent the backoff timer through using multiple sessions.
Solution
Configure the Minimum Session Time using the following command under the [edit system] hierarchy:
[edit system]
user@host#set login retry-options minimum-time
Default Value:
For most JUNOS version the default is a Minimum Session Time of 20 seconds.