How to configure Top Simple things in a Cisco Router using Command Line in the IOS

Dear Readers, Today I am sharing with you a few important things or top simple things to configure in a Cisco router. All the configurations in the Cisco Routers are very important but if you are a beginner user of Cisco devices particularly the Router or you just want to familiarize yourself with a Cisco Router or Perhaps you just want basic configurations for your home network then it's good you go through the few commands I shall share with you in this article. This will not be a complete command configuration but can help you set up basic things for a small home or office network. If you are a novice and just want to play around with one, then you can begin with this set of configurations that I will share here with you. If not interested in this literature, you can scroll down to THE COMMAND LINE and Check out what you might want to configure and how to do or configure it in the IOS.

Now, note Cisco is a Software Company, A lot of people don't know this, they know its a hardware networking company producing I.T Network devices, Servers, and Cybersecurity Solutions, etc. which of course is true but it is a software company and their Operating System is the Cisco IOS(Internetwork Operating System) which permits users to access and configure all internal components in their devices using CLI(the Command Line Interface). In short, the power of Cisco is in its IOS. There is a Graphic way of configuring Cisco devices Using the SDM(Security Device Manager) and stuffs like that, but it is limited and to me in my experience seems longer than just typing a few commands and getting what you want to configure done.

Cisco Router is one of the most popular Cisco devices and this is still the device that made Cisco so popular. Though Cisco was not the inventor of a Router, they were the first to mass-produce routers that could be used for commercial purposes and today there exist different series of routers that could be used according to the needs of the company, enterprise or corporation such as ISR 800, 900, 1000, 4000 Series for cloud-managed security, NCS 5000, 5500 series for Wan Connectivity and Machine to Machine(M2M), and ISRR which contains the 800, 900, 2000, 3000  and ISR 4221 for small, medium and large industrial companies respectively.

For this topic, I have classified the top and important things to configure under different categories which include Basic management, Security, and finally Routing. Also, note that there are three modes involved in the IOS for configuration i.e User mode, privilege mode, and Global Config mode. Advanced configurations and configurations that affect the entire device are done in the global configuration mode. With all these put in place let's begin. Remember to leave us a comment below if you need help with a command or better let's hear your thought about this post.

THE COMMAND LINE INTERFACE. The below interface used a teraterm terminal program.

Always keep in the mind the mode you are in, before or while configuring. Also, Cisco devices using the IOS always boot and start in the user-mode, configurations are done in the global config mode and show commands are done in the privilege mode. Press the enter key to validate any command you type. So let's begin...

You are in the user mode

= TO ACCESS THE PRIVILEGE MODE: type Enter or En
= TO ENTER GLOBAL CONFIG MODE: type Configuration terminal or config t
= TO SET UP A BANNER: type Banner motd (a delimiting character e.g @, x, %, & etc) Banner message e.g (unauthorized Access Restricted) Same delimiting character. this is an example of a banner command =
  Banner motd @ UNAUTHORISED ACCESS RESTRICTED @
= TO GIVE YOUR ROUTER A NAME: Type Hostname xx (where xx is the name of the switch)
= TO VIEW ALL INTERFACE OF A ROUTER: Go to privilege mode and type:
Show IP interface brief
= TO ASSIGN AN IP ADDRESS: Every interface of a router represents a network so the interface may either be a serial or FastEthernet or gigabitEthernet connection but all have the same command concept so, open the interface by typing INTERFACE FAx/x where x is the interface number e.g fa0/0, fa0/1, if its serial S0/0 and gigabit will be G0/0 etc. then follow with the command IP address x.x.x.x subnet mask. X is your 32 bit or 4 octet address. This is how the command should look like...
Interface fa0/0 [enter]
IP address 192.168.1.1 255.255.255.0 [enter]
no shutdown
= TO SAVE CONFIGURATIONS[privilege mode] Copy running-config{space} Startup-config
= TO VIEW SAVE CONFIGURATIONS[privilege mode] Show startup-config
= TO VIEW RUNNING CONFIGURATIONS[privilege mode] show running-config
= TO SETUP DHCP( Global config mode): Type
 Ip dhcp pool xx ( x is the name you want to give your pool) [enter]
Network x.x.x.x subnet mask(x is your network address, closely followed by the subnet mask)
default-router x.x.x.x (x is the router's IP address) [enter]
dns-server x.x.x.x( x is the IP address of the DNS server) [enter]
= TO KEEP STATUS MESSAGES FROM INTERRUPTING YOUR TYPING COMMANDS:
Line Console 0 [enter]
logging synchronous [enter] NOTE: you should also type this command unter the telnet port
= TO SETUP DNS(Global config mode) type:
ip domain-lookup [enter]
ip name-server x.x.x.x ( x is the IP address you want to give the DNS server) [enter]
ip domain-name www.xxxxxx.com ( x is your domain name e.g www.shanyelson.com)

= TO SETUP DHCP EXCLUDED ADDRESSES: (global config mode)
Ip dhcp excluded-address x.x.x.x{space}x.x.x.x
(x are the address ranges that DHCP will not assign to host machines, from x.x.x.x to x.x.x.x addresses)
= TO SET UP AN INTERNET WAN PORT(global config mode) go to the port interface that is connected to the internet and type:-
Interface FastEthernet x/x [enter] x/x is the port number on the router
IP address x.x.x.x subnet mask [enter] x.x.x.x is a bought static IP address given by your ISP.
no shutdown [enter]
If you don't have a static IP address, you can use the port dynamically i.e by the ISP's DHCP Server
so the command will be...
Interface FastEthernet x/x [enter] x/x is the Ethernet port number on the router
IP address dhcp [enter]
You can give the port a description so you can remember the link it's connected to by typing
Description xxxxx [enter] (xxxx is the name you will describe the link e.g WAN  Internet Link)

= TO EXIT ONE STEP OUT OF A CONFIGURATION: simply type EXIT
= TO EXIT OUT OF ONE MODE TOTALLY: simply type END
= TO SECURE THE PRIVILEGE MODE: Type Enable secret xxx( X is your password)
=TO SECURE THE CONSOLE PORT: type
Line Console 0 [enter]
password xx (x is your password) [enter]
Login
=TO SECURE THE VTY PORT: TYPE
Line vty 0 4 ( the range depends on your number of vty ports that you wish to secure
password xx (x is the name of your password)
Login
=TO SECURE THE AUXILLARY PORT:-(this port is used to attach a modem) type
Line Aux 0 [enter]
password xx (x is the name of your password)
login
=TO SETUP A TIME LAPSE BEFORE THE ROUTER LOGS OUT WHEN IDLE: Type
Line Con 0 [enter]
exec-timeout mm{space}ss (mm is minutes and ss is seconds)
= TO SETUP SSH: (Global config mode) type
Username xxx password xxx [enter] x is your user name and password respectively
IP domain-name www.xxxx.com [enter] put your domain name e.g www.shanyelson.com
crypto key generate rsa [enter]
512 or 1024[ Enter] (choose between 512bits or 1024 bits}
ip ssh version 2 [enter]
line vty 0 4 [enter]
transport input ssh [enter] NOTE: in some routers, you may have to type but
transport input telnet ssh
Also, note you can't successfully configure SSH without setting a hostname for your router
=TO COMPLETELY ENCRYPT ALL SET PASSWORDS: TYPE
Service password-encryption [enter]
=TO SETUP RIP: (global config mode) type
IP routing [enter]
Router rip [enter]
network x.x.x.x (x is your network IP address, list all your networks here and press enter after each)
=TO SET UP RIP VERSION 2
IP routing [enter]
Router rip [enter]
version 2 [enter]
network x.x.x.x (x is your network IP address, list all your networks here and press enter after each)

=TO SETUP OSPF: (global config mode) type

IP routing [enter]

router ospf x [enter] x is the process id which ranges from 1 to 65535

Network x.x.x.x wildcard bits(a reverse format of the subnet mask) Area number [enter]

this is a typical example: network 192.168.1.0 0.0.0.255 area 0  NOTE: choose any number for the area number but it should be the same number for all the network addresses that will be listed

= TO SETUP EIGRP: (global config mode) type

IP routing [enter]

router eigrp x (x is an autonomous number between 65535

network x.x.x.x ( x is your network IP address. list them all here, pressing ENTER after each)

To remove any command, Type NO before the command for example if you do not want rip to continue running you can go to global config and type NO router rip. NO negates any command.

So this wraps up the basic commands and configurations for your router if you just want the simple things to do on your Router and get it running then this is just best for you. Feel free to leave your comments and if you face difficulties while configuring, you can also drop them in the comments section. Note that these are basic configurations, I will prepare more advanced configurations like setting frame relay, PPP, Authentications, NAT, VPN, ACLs, WAN configurations in general. These commands are only for routers. the next will be for switches but still, though, they do have some similar commands. To get a full analysis of your router, you can type:

Show version in the privilege mode and you can see that. There are a host of other show commands and all these show commands are done in the privilege mode.

show cdp neighbors = to see directly connected devices

Show cdp neighbor detail =  To see full details of directly connected devices

show IP protocol = to see all currently configured routing protocols