You want to display a banner during login that indicates that the router is for authorized users only.
You define a login banner:
[edit system login] aviva@router1# set message " n========================================================== Access to this device is limited to authorized users only. WARNING: All unauthorized access is prohibited. ================================================= ========= "
A login banner is displayed each time anyone logs in to the router, before the login prompt:
aviva-server% telnet router1 ========================================================== Access to this device is limited to authorized users only. WARNING: All unauthorized access is prohibited. ========================================================== router1 (ttyp0) login:
It may seem rather trivial to set a login banner, and you may wonder what this has to do with router security because it doesn't do anything to restrict access to the router. Although this is true, having a login banner is good practice for legally protect your router. From a legal point of view, you want to warn unauthorized users that they are not permitted to use the router and you want to do so with a strongly worded message, as we've shown here. While you might think that you want to welcome users to the router, you should not use the word "welcome" or any similar words in the login banner.
You can also have a login message that is displayed after users log in to the router:
[edit system] aviva@router1# set announcement "Reminder: maintenance window schedule at 0200 UTC"
These messages are a way to remind authorized users of network or router issues:
aviva-server1% telnet router1 router1 (ttyp0) login: aviva password: ******** --- JUNOS 7.4R1.7 built by builder on 2005-10-23 02:03:58 UTC Reminder: maintenance window schedule at 0200 UTC aviva@router1>
Router Configuration and File Management
Basic Router Security and Access Control
Routing Policy and Firewall Filters