Skip to content

Latest commit

 

History

History
183 lines (148 loc) · 7.21 KB

introduction.md

File metadata and controls

183 lines (148 loc) · 7.21 KB
Raw

Introduction

The command line interface (CLI, see-ell-aye) implements a CISCO-like, or Juniper Networks JunOS-like, CLI. It is the traditional way of interacting with single network equipment like switches and routers. Today more advanced graphical NETCONF-based tools are available that allows for managing entire fleets of installed equipment.

Nevertheless, when it comes to initial deployment and debugging, it is very useful to know how to navigate and use the CLI. This very short guide intends to help you with that.

About

New users usually get the CLI as the default "shell" when logging in, but the default admin user logs in to bash. To access the CLI, type:

admin@host-12-34-56:~$ cli

See the 'help' command for an introduction to the system

admin@host-12-34-56:/>

The prompt (beginning of the line) changes slightly. Key commands available in any context are:

admin@host-12-34-56:/> help                   # Try: Tab or ?
...
admin@host-12-34-56:/> show                   # Try: Tab or ?
admin@host-12-34-56:/>                        # Try: Tab or ?

Tip: Even on an empty command line you can tap the Tab or ? keys. See help keybindings for more tips!

Key Concepts

The two modes in the CLI are the admin-exec and the configure context.

The top-level context after logging in and starting the CLI is the admin-exec or "main" context. It is used for querying system status, managing configuration files/profiles and doing advanced debugging.

Available commands can be seen by pressing ? at the prompt:

admin@host:/>
  configure      Create new candidate-config based on running-config
  copy           Copy file or configuration, e.g., copy running-config startup-config
  dir            List available configuration files
  exit           Exit from CLI (log out)
  factory-reset  Restore the system to factory default state
  follow         Monitor a log file, use Ctrl-C to abort
  help           Help system (try also the '?' key)
  logout         Alias to exit
  netcalc        IP subnet calculator, with subnetting
  password       Password tools
  ping           Ping a network host or multicast group
  poweroff       Poweroff system (system policy may yield reboot)
  reboot         Reboot system
  remove         Remove a configuration file
  set            Set operations, e.g., current date/time
  show           Show system status and configuration files
  tcpdump        Capture network traffic
  upgrade        Install a software update bundle from remote or local file

The system has three main datastores (or files): factory, startup, and running that can be managed and inspected using the copy, show, and configure commands. The traditional names used in the CLI for these are listed below:

  • factory-config the default configuration from factory for the device, i.e., what the system returns to after a factory-reset
  • startup-config created from factory-config at first boot after factory reset. Loaded as the system configuration on each boot
  • running-config what is actively running on the system. If no changes have been made since boot, it is the same as startup-config
  • candidate-config is created from running-config when entering the configure context. Any changes made here can be discarded (abort, rollback) or committed (commit, leave) to running-config

Edit the running configuration using the configure command. This copies running to candidate, a temporary datastore, where changes are made:

admin@host-12-34-56:/> configure
admin@host-12-34-56:/config/> ...             # Try: Tab or ?
admin@host-12-34-56:/config/> leave

The leave command activates the changes by issuing a transaction to, essentially, copy the candidate back to running. Depending on the changes made, this can take a few seconds. If the changes are invalid, i.e., not correct according to the underlying YANG models, a warning is shown and the session remains in configure context. Use the abort command to cancel your changes, or investigate further with the diff command (see more below).

To save configuration changes made to the running-config to persistent store, so the system will use them for consecutive reboots, use the copy command:

admin@host-12-34-56:/> copy running-config startup-config

In configure context the following commands are available:

Command Description
set foo bar val Set bar leaf node in foo subcontext to val
no foo bar Clear/delete configuration made to bar in foo
edit foo baz Enter baz sub-sub-context in foo subcontext
change password Start password dialogue to change a user's password
text-editor foo Open a text editor to edit binary setting foo
abort Abort changes in configuration, return to admin-exec
exit Exit one level sub-context, or abort from top-level
leave Save changes to running-config, return to admin-exec
show [foo] Show configured values (optionally in subcontext)
diff [foo] Show uncommitted changes in candidate
do command Call admin-exec command: do show log
commit

Example Session

Remember to use the TAB and ? keys to speed up your navigation. See help keybindings for more tips!

In this example we enter configure context to add an IPv4 address to interface eth0, then we apply the changes using the leave command.

We inspect the system status to ensure the change took effect. Then we save the changes for the next reboot.

admin@host-12-34-56:/> configure
admin@host-12-34-56:/config/> edit interface eth0
admin@host-12-34-56:/config/interface/eth0/> set ipv4 <TAB>
      address     autoconf bind-ni-name      enabled
	  forwarding  mtu      neighbor
admin@host-12-34-56:/config/interface/eth0/> set ipv4 address 192.168.2.200 prefix-length 24
admin@host-12-34-56:/config/interface/eth0/> show
type ethernetCsmacd;
ipv4 address 192.168.2.200 prefix-length 24;
ipv6 enabled true;
admin@host-12-34-56:/config/interface/eth0/> diff
interfaces {
  interface eth0 {
+    ipv4 {
+      address 192.168.2.200 {
+        prefix-length 24;
+      }
+    }
  }
}
admin@host-12-34-56:/config/interface/eth0/> leave
admin@host-12-34-56:/> show interfaces brief
lo               UNKNOWN        00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
eth0             UP             52:54:00:12:34:56 <BROADCAST,MULTICAST,UP,LOWER_UP>
admin@host-12-34-56:/> show ip brief
lo               UNKNOWN        127.0.0.1/8 ::1/128
eth0             UP             192.168.2.200/24 fe80::5054:ff:fe12:3456/64
admin@host-12-34-56:/> copy running-config startup-config

One of the ideas behind a separate running and startup configuration is to be able to verify a configuration change. In case of an inadvertent change that, e.g., breaks networking, it is trivial to revert back by:

admin@host-12-34-56:/> copy startup-config running-config

Or restarting the device.