Subtitles of the Movie

Network Management from the Command Line. There are several commands which can help you configure network cards. In this video we'll discuss the ifconfig, iwconfig, iwlist, route, ifup, ifdown, as well as network managers NM Tool command. First there's the ifconfig command. Run by itself, it displays the current status of all configured network cards. When run with the name of the interface, in this case Eth0, you can focus in on a specific network card. And with administrative privileges, you can specify a new IP address and if you prefer, a different network mask. Next there are the wireless network configuration commands: iwconfig and iwlist. The iwconfig command by itself is similar to the ifconfig command as it checks the wireless characteristics of all configured network cards. You could use it to change the connected network access point; specifically the ESSID, which is short for the Extended Service Set Identifier. If my wireless card is Eth0, the command shown here, sudoiwconfigEth0 ESSID Nancy Randy changes the network to the Nancy Randy network. In a number of public locations I've run the iwconfig command and I see a bunch of wireless networks and what happens, say, two of them have the same name, such as default. Then I could connect to the preferred network by specifying the wireless network hardware address. But how do you find that hardware address? That, as well as the ESSID is available courtesy of the iwlist command, as shown here. Next there is the route command. When run by itself, it shows default routes. I prefer to run it with the n switch as that ensures that the routes are taken in numeric format. I can delete a default route but I don't have one yet so let's go to Add a Default Route. I add a default route through my gateway system, which is available at address 192.168.0.1. I confirm the changes and I see I have a new gateway. I can reverse the process by deleting the default route with the following command. I confirm the result and my default route is now deleted. Now let's examine the ifup and ifdown commands. Since networking is activated on this system, let's first deactivate networking. It requires administrative privileges. The AV switch deactivates all network interfaces in verbose mode. Watch is it first deactivates the loopback interface, runs several scripts in the DC/network directory, deactivates the active Ethernet interface and deletes the default route. Let's reverse the process and reactivate the network. Let's scroll back a bit. The command activated the loopback interface, assigned the loopback address of 127.0.0.1. It also runs several scripts in the etc/network directory, activates the first Ethernet interface with a specific mask and broadcast address, courtesy of what's available in the etc/network interfaces files and it finally adds a default route with a given gateway address. Finally there are the commands associated with the Network Manager. It allows automatic searches and connections. It also supports whatever preferences you set from the GUI. But the GUI part of the Network Manager is trivial; just right click on the network icon. In contrast, the Network Manager package includes the NM Tool command, which can track the status of all local network devices. Properly configured, it can also display the driver, the hardware address and wireless capabilities of the card if so configured.