Configuring Junos OS for the First Time on a Device with a Single Routing Engine
To configure the Junos OS for the first time on a router with a single Routing Engine and no base configuration, follow these steps:
- Connect to the device through the console port.
- Power on the device and wait for it to boot.
The Junos OS boots automatically. The boot process is complete when you see the
login:prompt on the console. - Log in as the user
root.Initially, the
rootuser account requires no password. You can see that you are therootuser, because the prompt on the device shows the usernameroot@#. - Start the Junos OS command-line interface (CLI):
root@# cli root@>
- Enter Junos OS configuration mode:
cli> configure [edit] root@#
- Configure the hostname of the device.
We do not recommend spaces in the router name. However, if the name
does include spaces, enclose the entire name in quotation marks ("
").
[edit] root@# set system host-name hostname
- Set the root password, entering either a clear-text password
that the system will encrypt, a password that is already encrypted,
or an SSH public key string.
Choose one of the following:
To enter a clear-text password, use the following command:
[edit] root@# set system root-authentication plain-text-password New password: type password Retype new password: retype password
To enter a password that is already encrypted, use the following command:
[edit] root@# set system root-authentication encrypted-password encrypted-password
To enter an SSH public key, use the following command:
[edit] root@# set system root-authentication ssh-rsa key
- Configure the device domain name:
[edit] root@# set system domain-name domain-name
Note:Before you begin the next step, see Supported Routing Engines by Router to find the management Ethernet interface that you should use to perform this configuration.
- Configure the IP address and prefix length
for the device management Ethernet interface. The management Ethernet
interface provides a separate out-of-band management network for the
device.
For devices that use management Ethernet interface fxp0:
[edit] root@# set interfaces fxp0 unit 0 family inet address address/prefix-length
For devices that use management Ethernet interface em0:
[edit] root@# set interfaces em0 unit 0 family inet address address/prefix-length
- Configure the IP address of a backup or default network
device. Choose a device that is directly connected to the local router
by way of the management interface. This backup is used only when
it is booting and only or when the Junos routing software (the routing
protocol process, rpd) is not running.
For devices with two Routing Engines, the backup Routing Engine,
RE1, uses the backup device as a default gateway after the device boots. This enables you to access the backup Routing Engine. (RE0is the default primary Routing Engine.)Note:The backup Routing Engine does not support more than 16 backup routing destinations. If you configure more than 16 destinations on the backup Routing Engine, the Junos OS ignores any destination addresses after the sixteenth address and displays a commit-time warning message to this effect.
[edit] root@# set system backup-router address
- Configure the IP address of a DNS server. The router uses
the DNS name server to translate hostnames into IP addresses.
[edit] root@# set system name-server address
- Optionally, display the configuration
statements:
[edit] root@ show system { host-name hostname; domain-name domain.name; backup-router address; root-authentication { (encrypted-password "password" | public-key); ssh-dsa "public-key"; ssh-ecdsa "public-key"; ssh-rsa "public-key"; } name-server { address; } interfaces { fxp0 { unit 0 { family inet { address address ; } } } } }On devices that use management Ethernet interface em0, you will see em0 in place of fxp0 in the
showcommand output. - Commit the configuration, which activates the configuration
on the device:
[edit] root@# commit
After committing the configuration, you see the newly configured hostname appear after the username in the prompt—for example,
user@hostname#.A basic configuration for Junos OS is now set on the device.
If you want to configure additional Junos OS properties at this time, remain in the CLI configuration mode and add the necessary configuration statements. You need to commit your configuration changes to activate them on the device.
- Exit from the CLI configuration mode.
[edit] root@hostname# exit root@hostname>
- Back up the configuration.
After you have committed the configuration and are satisfied that the new configuration is successfully running, you should issue the
request system snapshotcommand to back up the new software to the /altconfig file system. If you do not issue therequest system snapshotcommand, the configuration on the alternate boot device will be out of sync with the configuration on the primary boot device.The
request system snapshotcommand causes the root file system to be backed up to /altroot, and /config to be backed up to /altconfig. The root and /config file systems are on the device’s CompactFlash card, and the /altroot and /altconfig file systems are on the device’s hard drive.Note:After you issue the
request system snapshotcommand, you cannot easily return to the previous configuration, because the running copy and the backup copies are identical.