Junos Device Hardening: Beyond the Basics

In this blog post, we will delve deeper into the topic of Junos device hardening, a crucial aspect of the JNCIS-ENT certification. Junos device hardening refers to the process of securing a Junos device by reducing its surface of vulnerability. This is achieved by eliminating unnecessary access and services, ensuring the device is updated with the latest security patches, and configuring the device securely.

Secure Access

One of the first steps in hardening a Junos device is to secure access to the device. This can be achieved by using secure protocols for device management, such as SSH and HTTPS, instead of insecure protocols like Telnet and HTTP.

set system services ssh
set system services web-management https

In addition, it is recommended to restrict access to the device by using access control lists (ACLs). This can be done by defining firewall filters and applying them to the loopback interface.

set firewall family inet filter MANAGEMENT-ACL term ALLOW-SSH from source-address 192.0.2.0/24
set firewall family inet filter MANAGEMENT-ACL term ALLOW-SSH from protocol tcp
set firewall family inet filter MANAGEMENT-ACL term ALLOW-SSH from port ssh
set firewall family inet filter MANAGEMENT-ACL term ALLOW-SSH then accept
set interfaces lo0 unit 0 family inet filter input MANAGEMENT-ACL

Disable Unnecessary Services

Another important step in hardening a Junos device is to disable unnecessary services. By default, a Junos device has several services enabled that may not be necessary in a production environment. These services can be disabled using the delete system services command.

delete system services telnet
delete system services ftp
delete system services netconf ssh

Secure System Basics

In addition to securing access and disabling unnecessary services, there are several other basic system configurations that can be used to harden a Junos device.

Firstly, it is recommended to set a strong root password. This can be done using the set system root-authentication command.

set system root-authentication encrypted-password "$1$./4BcDEfG$hT7xJcTijLk7t7.K4cDEf0"

Secondly, it is recommended to enable system logging and configure it to log security events. This can be done using the set system syslog command.

set system syslog user * any emergency
set system syslog file messages any notice
set system syslog file messages authorization info

Lastly, it is recommended to keep the Junos device updated with the latest security patches. This can be done by regularly checking the Juniper Networks website for security advisories and applying the necessary patches.

In conclusion, Junos device hardening is a crucial aspect of network security and a key topic in the JNCIS-ENT certification. By securing access, disabling unnecessary services, and following basic system security practices, you can significantly reduce the surface of vulnerability of your Junos devices.