Router tutorial

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Introduction

A router is an electronic network equipment used to connect two or more computer networks.

In the OSI hierarchy, routers work on level 3. Uses IP addresses for switching packets.Optimizing routing is done using routing tables.
These can be static (operator-created), or dynamic, learned from neighboring routers based on routing protocols.
Routers can be:
- individual, used to connect a home to the Internet. They are small, inexpensive, connect via DSL, coaxial cable or FO to the provider, they also have an integrated switch (multiple Ethernet ports) and have wireless access point (creating a wi-fi local network) .
They generally have their own operating system (depending on the manufacturer), and setup is easy using the Graphical User Interface (GUI).
- for companies that are big, robust and can interconnect many networks. The most used in telecommunication companies is the Cisco router (with IOS operating system).


HG824 Router (Huawei)

The WAN interface to connect to the provider is GPON, using FO. The router includes an integrated switch that has 4 Ethernet ports. It can also create and manage a wi-fi local network.
- The connection is made by typing in the browser: 192.168.100.1 (default IP address).


HG

Type user: root and password: admin and connect:


HG

First configure the WAN interface to the IP provider and IP assignment mode (static or DHCP).


HG

Then we configure the Local Area Network, the router's IP address being: 192.168.100.1 and a gateway to WAN for other PCs and devices in the LAN.


HG

We enable and set up DHCP so that other network devices automatically take their IP from the router's access point.


HG

From the WLAN menu we will configure the password and coding mode for wi-fi internet access to devices.


HG

In the Security menus, we can set some filters to restrict access from the Internet (WAN) to the local area network (LAN). Thus, we can filter IPs, MAC addresses or URLs (websites) that can not access the devices in the LAN.
IP filters are set in the following menu:


HG

In the Security DoS (Denial of Services) menu, filters are set for different types of external attacks:


HG

In the Forward Rules menu, there are DMZ, Port Mapping and Port Trigger menus.
From the DMZ (Demilitarized Zone) menu, you can restrict some devices from LAN to WAN:


HG

From port mapping (also known as Port Forwarding), port correspondence is set for different devices (IPs) and different applications.
Thus, from the Internet, we can access different applications from different PCs in the LAN, using the fixed IP of the router (on the WAN interface), but on different ports (for example: 109.98.11.250/8080).


HG

In the Network Applications menu, we can configure different applications, such as: FTP client (for downloading files from the local network and saving to a USB stick), ARP, IGMP, QoS or DNS.


HG

In the System Tools menu, we can reset the router, see the logs, make the default configuration restore, power management:


HG

The Status menu is used for information about WAN, VoIP, WLAN, Ethernet port, Battery.


HG

DHCP information:


HG

Also, information about the Optical Interface (GPON):


HG

Router RT-AC52U_B1 (Asus)

It is a dual-band router, equipped with 5th generation Wi-Fi (5G Wi-Fi) technology.
With 2.4 GHz, it reaches speeds of 300 Mbps, while the 5GHz band allows speeds of up to 433 Mbps.
Through the built-in USB port, external storage devices, printers and other electronic products can be connected and can be easily shared within the network.
To configure the router, type in the browser: 192.168.1.1. The login window opens.


Asus

Introduce user: admin and password: admin and connect us. In the first image are shown some of the menus:


Asus

And the rest of the menus:


Asus

First we set the WAN interface of the router (uplink from the provider).


Asus

Also in the WAN section we can set the DMZ (demilitarized zone), to restrict traffic to a local network (LAN) device.


Asus

Now we set up the local area network (LAN):
Asus

And we can set up DHCP (which automatically assigns IPs to devices connected to the LAN):


Asus

The local Wi-Fi network is set in the window:


Asus

We can set up a private network (VPN):


Asus

We can use parental control (to restrict certain sites):


Asus

We can set the USB interface:


Asus

We can set firewall:


Asus

IPv6 addresses can be set:


Asus

Can set Asus cloud:


Asus

Port forwarding can be done:


Asus

We can watch the network:


Asus

We can get information about visitors:


Asus

We can get traffic information:


Asus

We can look at logs:


Asus

We can use the tools offered by Asus: ping, netstat, etc .:


Asus

We also have a management window, where we can update the software, save, modify, load configurations, work with files:


Asus

Cisco Router

For large telecommunication networks, for large routing capabilities, Cisco routers are used.
Cisco routers, although having their own operating system (IOS), do not have a graphical user interface (GUI).
Configuration is done through the console (on installation), after which the router can be accessed via SSH or Telnet.
So, if we connect via serial cable (RS232), we can use Putty to gain access to the console.


Putty serial

We set the initial parameters and connect.
The prompt will appear:


Router>


There are multiple access levels protected by passwords with different privileges.
Now we are in the: user exec mode.
To move to the next level (privileged mode), we will type: enable, and the prompt will change:


Router#


For: global configuration mode, type: configure terminal, and the prompt will change:


Router(config)#


In: global configuration mode, the router is configured.
Examples of commands:


show?

- All available commands are displayed.


show running-config

- The current configuration file is displayed.


show running-config startup-config

- Copy the current configuration file (from RAM) to non-volatile memory (NVRAM). It has the role of saving the configuration.


erase startup-config (followed by the command: reload)

- Delete the configuration file (after reset, the router is as new).


show interface X

- The parameters of the X interface are displayed.


show ip interface brief

- All the interfaces present on the router are displayed.


hostname X

- Set the router's name as X.


username abc privilege 15 password xyz

- A new abc user with level 15 privileges and the xyz password is set.


line vty 0

- Configuring Telnet access. The prompt will change to: config-line #


Using the Tab key makes the completion of the command.


Example of Configuring an Interface

Router>enable
Router#configure terminal
Router(config)#interface fastEthernet 0/0
Router(config-if)#ip address 192.168.1.1 255.255.255.0
Router(config-if)#no shutdown
Router(config-if)#exit
Router(config)#


Cisco has developed a program called Packet Tracer that once installed can test networks consisting of routers, PCs, access points, configurable interfaces, and simulate traffic.


Configuration for Telnet and SSH access (privilege level 15)

Router(config)# line vty 0 5
Router(config-line)# privilege level 15
Router(config-line)# login local
Router(config-line)# transport input telnet
Router(config-line)# transport input telnet ssh
Router(config-line)# exit


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