Knowledge book: cisco router configuration tutorial

How can we really configure cisco routers? Next we will give you a detailed introduction to this issue. In fact, there is no need to make the router think so complicated. In fact, the router is a computer with multiple ports, but it plays a different role in the network than the general PC.

Like a common computer, a router also needs an operating system. cisco calls this operating system a cisco interconnected network operating system, which is known as IOS, all cisco routers are configured with an embedded software architecture. The ciscoIOS software provides the following network services: basic routing and switching functions, reliable and secure access to network resources, and scalable network structure. The cisco command line interface (CLI) uses a hierarchical structure that completes specific tasks in different modes. For example, to configure a vro interface, you must enter the interface configuration mode of the vro. All configurations are only applied to this interface. Each configuration mode has a specific command prompt. EXEC provides a command interpretation service for IOS software. When each command is typed, EXEC will execute this command.

When we configure the cisco router for the first time, we need to configure it from the console port. Next, we will introduce how to connect to the control port and set the virtual terminal program. Use the rolover line and a RJ45 and DB9 or DB25 conversion adapter to connect the router control port and terminal computer. How to connect to the control port of the cisco router: the control port consoleport and the Auxiliary port (AUXport) are the two management ports of the cisco router, both of which can be used for the first cisco router configuration, however, we generally recommend that you use control ports because not all routers have AUX ports.
When a vro is started for the first time, there are no network parameters by default, and the vro cannot communicate with any network. So we need a RS-232ASCLL terminal or computer simulation ASCLL terminal and control port connection.

Method to connect to the CONSOLE port: connect to the console port we need an adapter for rolover cable and RJ-45 to DB-9. We can see this in the product attachment of the cisco router. Terminal simulation software: the PC or terminal must support the VT100 simulation terminal. Usually HyperTerminal software is used in the WindowsOS environment. Here we take the host name as riga as an example. In Global mode, enter "hostnameriga" and press the Enter key to execute the command. Then, the host name before the host prompt changes to riga, indicating that the host name is successfully set.

How to enter the cisco router configuration mode
The command line port of a cisco router uses a hierarchical structure, which requires logging on to different modes to complete detailed configuration tasks. From a security perspective, ciscoIOS divides EXEC sessions into USER mode and privileged mode.

Features of USER mode
Only basic monitoring commands are allowed in USER mode. In this mode, the configuration of the cisco router cannot be changed. The command prompt of router> indicates that the USER is in USER mode.

Features of privileged Mode
In privileged mode, you can use all the configuration commands. In user mode, a password is generally required to access privileged mode. The command prompt of router # indicates that the user is in privileged mode.

Cisco router configuration mode
In user mode, users can only display router information, but cannot change any cisco router configuration. To use all commands, you must enter the privileged mode. In privileged mode, you can also enter global mode and other special configuration modes, which are a subset of global mode.

How to enter privileged Mode
After the first successful startup, the cisco router prompts the user mode prompt router>. If you want to enter the privileged mode, you do not need a password when you type the enable command to start the router for the first time ). At this time, the command prompt of the router is changed to router #.

How to enter global Mode
After entering the privileged mode, we can enter the configureterminal command at the privileged command prompt to perform the global configuration mode.

How to enter the port configuration mode
Enter interfacee0 at the global command prompt to enter the first Ethernet port, and enter interfaceserial0 to enter the first serial line port. The above briefly introduces how to enter the various configuration modes of the Cisco router. Of course, other special configuration modes can be entered in global mode. In the configuration process, we can use? To obtain command help.

Cisco router configuration Password
In CISCO router products, we usually need to restrict the access of general users during initial configuration. This is very important for cisco router configuration. By default, our router is an open system and the access control options are all disabled, any user can log on to the device to initiate further attacks, therefore, our network administrator needs to configure a password to restrict unauthorized users from accessing devices through direct connections, CONSOLE terminals, and dial-up MODEM lines. Next we will introduce in detail how to configure the vro password on the CISCO router product.