Discussion

While the configuration shown in this recipe provides the minimum needed to access
the router from another system on the network, you should add a few other settings
to the configuration to provide a more robust level of basic network connectivity:
[edit]
root@router1# set system ntp server 192.168.2.100
root@router1# set system time-zone America/Los_Angeles
root@router1# set system services ssh
root@router1# set interfaces lo0 unit 0 family inet address 207.17.139.42/32
root@router1# set system login user aviva class superuser
root@router1# set system log user aviva authentication plain-text-password
New password:
Retype new password:
root@router1# commit
The first command, set system ntp server, configures the IP address of an NTP
server so that the router can set its time properly. Because we have already configured
DNS on the router, you could specify the name of the time server instead of an
IP address and it will be translated to an IP address. To have the router obtain accurate
time from the servers, it is good practice to configure a minimum of four NTP
servers. You can also optionally configure the time zone in which the router is
located (see Recipe 6.2); by default, the time zone is UTC.
To be able to log in to the router over the network using SSH, enable SSH services on
the router with the set system services ssh command. For this to work, SSH must
also be configured on the network servers. SSH is also used to copy files to and from
the router. (The JUNOS SSH uses the Unix scp command.) Note that you can also
copy files with FTP or HTTP (see Recipe 2.1), but these are less secure than SSH. On
routers with two Routing Engines, you can copy files between the two (see Recipe 1.30).
The set interfaces command sets the router’s IP address by configuring an address on
the loopback interface (see Recipe 7.3). The last two commands set up a non-root
user account so an individual user can log in to the router (see Recipe 2.5).
If your router has two Routing Engines, you also need to configure a hostname and
IP address for the second Routing Engine (see Recipe 1.30).
Again, issue the commit command for the configuration changes to take effect:
root@router1# commit
Recipes 1.7, 1.15, and 1.16 explain how the commit operation works, including how
to provisionally commit configuration changes.
At this point, you are logged in to the router as the user root, so you have complete
control over the router. As root, you can perform operational actions that shut down
the router or make it inaccessible to the network. While there are times when you
want to legitimately perform these types of operations, you generally want to make
sure that the router continues to operate normally, and you want to minimize the
chance of accidentally interfering with the router’s operation.
16 | Chapter 1: Router Configuration and File Management
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