Protect

Configure Passwords to Secure Cisco Router

How to password protect Console Port

To configure the console password, follow these steps.

Router(config)# line console 0
Router(config-line)# password CISCO
Router(config-line)# login
Router(config-line#Ctrl-Z
Router#

How to password protect Auxilary (AUX Port) Port

To configure the auxilary password, follow these steps.

Router#config t
Router(config)#line aux 0
Router(config-line)#password cisco
Router(config-line)#login
Router(config-line)# Ctrl-Z
Router#

How to password protect VTY Ports (Telnet Ports)

Configuring the VTY password is very similar to doing the Console and Aux ones. The only difference is that there are 5 VTY virtual ports, which are named 0, 1, 2, 3, and 4. You can use the shortcut 0 4 (a zero, a space, and 4) to set all 5 passwords at the same time. To configure the VTY password, follow these steps.

Router#config t
Router(config)#line vty 0 4
Router(config-line)#password cisco
Router(config-line)#login
Router(config-line)# Ctrl-Z
Router#

How to password protect Privileged Mode

The Enable Password is the old form of the password for “Privileged Mode”. Here the password is stored un-encrypted.

Router#config t
Router(config)#enable password cisco
Router(config-line)# Ctrl-Z
Router#

Enable Secret provides better security since password is kept encrypted using irreversible encryption algorithm.

Router#config t
Router(config)#enable secret cisco
Router(config-line)# Ctrl-Z
Router#

 Posted By – RamCruiseWalker

Lessons

Trivial File Transfer Protocol (TFTP)

Trivial File Transfer Protocol (TFTP) is a file transfer protocol, which is the basic form of File Transfer Protocol (FTP).

Trivial File Transfer Protocol (TFTP) has a very simple design and it requires only a very small amount of memory.

Trivial File Transfer Protocol (TFTP) is mainly used for network booting of computers and network infrastructure devices such as routers and switches.

Trivial File Transfer Protocol (TFTP) is used in Cisco networking environment to back up Cisco IOS (Operating System) image file, configuration files, Network Booting and for an IOS upgrade.

Trivial File Transfer Protocol (TFTP) is a simple file transfer protocol and it is implemented on top of the User Datagram Protocol (UDP). The standard UDP port number for Trivial File Transfer Protocol (TFTP) is 69.

Many Trivial File Transfer Protocol (TFTP) server software products for windows Operating System are available for free download on the Internet. Some are listed below.

Solarwinds Trivial File Transfer Protocol (TFTP) server

tftpd32 Trivial File Transfer Protocol (TFTP) server

Open Trivial File Transfer Protocol (TFTP) server

Posted By – RamCruiseWalker

Communicate With Router

Communicate With Router

Communicate with a Router using Console, Auxiliary, Telnet, SSH, HTTP and HTTPS connections

                            Routers are special computers built to handle internetwork traffic. Routers are very important network infrastructure devices and they serve many users at same time. The end users ho not communicate with the routers, but the network traffic generated by the end users communicate through the router.

                      There are no input devices for router like a monitor, a keyboard, or a mouse. An administrator can choose any of the following methods to communicate with the router.

Connection by using Console Port:

                            By connecting the router’s console port to a workstation through a console cable. The console port is the management port which is used by administrators to log into a router directly-that without using a network connection. You require a terminal emulator application like Hyperterminal or PuTTY to connect to router. Console port connection is a way to connect to the router when a router cannot be accessed over the network.  

Connection by using Auxiliary Port (AUX Port):

                         By using a remote computer through a modem that calls another modem connected to the router with a cable using the Auxiliary Port on the router. Auxiliary Port (AUX Port) allows a direct, non-network connection to the router, from a remote location. The Auxiliary Port (AUX Port) uses a connector type to which modems can plug into, which allows an administrator from a remote location to access the router like a console port.

Connection by using protocols like telnet, SSH, HTTP or HTTPS:

                          The routers can be managed over the network by using standard TCP/IP protocols like Telnet, SSH, HTTP or HTTPS. Telnet was developed in the early days of the UNIX operating system to manage computers remotely. A Telnet client and server application ships with Cisco’s IOS software and most computer operating systems. SSH is a more secure way to configure routers, since the SSH communication is encrypted. Cisco IOS also has a HTTP server to managed web based communication with the router.
Posted By – RamCruiseWalker
TCP/IP & OSI

TCP/IP And OSI Model

         TCP/IP and the OSI Model

Overview

                      In the previous chapter we were introduced to computer networks and we got to know their importance in everyday lives. In this chapter, we will look at the layered models that are used in communication over networks.

 

Layer Models

To better understand the various protocols and how they work with each other, we use layered models. A layered model shows how the protocols work at each layer as well as how the layers interact with the layers either above them or below them. The layered models that are used in modern computer networks are two; the OSI model (Open Systems Interconnection) and the TCP/IP model (Transmission Control Protocol/ Internet Protocol)

 There are several benefits that to using the OSI and TCP/IP models in explaining how network protocols work and these include the following.

  • Each layer in a model defines different protocols, therefore by using a layered model, network engineers can be able to define and design protocols which conform to the specific layer.
  • Competitions between different vendors is increased, this is because the models define standards and therefore product superiority is not based on the use of certain protocols since all products support them.
  • The layered model is useful since it allows for independence between other layers. This means that if a change in technology or capabilities is made in one layer, it will not affect another layer either above it or below it.
  • Since the layered model is an open standard, it provides for conformity and interoperability between different networking devices.
 

OSI Model

The OSI model provides an extensive list of functions and services that can occur at each layer. It also describes the interaction of each layer with the layers directly above and below it.

TCP/IP Model

                                        This model was first introduced in the 1970’s. There are four categories as you can see from the output above. Network communications were first defined using this model and for successful communication to occur, the functions of each layer must be in place in a network.

     From the output below, you can see the function of each and every layer of this model. The application layer, is the component that interfaces with the user, when you are using a web browser, this is a component of the application layer

The transport layer defines the various ports and helps differentiate the different types of communication from a single user. You may be sending an email, browsing and listening to internet radio on one computer. It is the work of the transport layer to differentiate the different types of communications. The transport layer also helps in interoperability between different network devices such as a PDA and a computer.

 The internet layer is meant to provide the best path to remote networks, this differentiates the different devices on a network. If a message is to be sent from one computer to another on a remote network, it is the work of the internet layer to make sure the message gets to the intended recipient. You may compare the internet layer to an address you use when you want to send a letter.

  The network access layer acts as an interface between the hardware and software components in the network. The application, transport and internet layers are all implemented by software, however, the network access translates the messages from these layers to a form that can be transmitted over various media such as fiber optic cables, copper wire and wirelessly.

 The protocols that are defined in the TCP/IP model describe the various functions and processes at each layer. This means that the protocols at each layer have to have specific functions as described by the TCP/IP model.
 

Process: 

1. At the application layer, we would create the email and this would be the data that would be communicated over the network.

2. The transport layer would then break this data into segments and add information in a process known as encapsulation.

3.The segments would then be passed down to the internet layer and encapsulated into packets, in this layer, logical addressing would be added. (more on logical addressing will be discussed later)

4.The packets would then be passed to the network access layer, the network access layer would then prepare the packets for transmission over the physical media such as fiber optic cable by converting the data to light signals.

5.When the data is received at the destination, the reverse process would happen, i.e., removal of protocol specific information – decapsulation as well as reassembly into the application data would be carried out.

6.The data would then be passed to the user. This process is illustrated below.

TCP/IP and OSI Model

  1. Data – the end user information, this may include, email content, website information among others. This is the information presented to the user.
  2. Segment – as mentioned earlier, this is the PDU at the transport layer.
  3. Packet – in the internetwork layer, the packets are the PDUs and they include the logical addressing for remote delivery.
  4. Frame – this is the form that data at the network access layer takes, there is also addressing at this layer which is physical addressing such as the MAC address.
  5. Bits – the form that is carried over the physical media form is Bits, these may be in many forms such as electrical signals, light signals and others.

PDUs and communication over a layered mode

The OSI model defines how messages are encoded, formatted, encapsulated, and segmented so that they can be transmitted over networks. As we mentioned earlier, the data is usually broken down into different PDUs and the layers in the OSI model define how each PDU is controlled so as to make communication successful.

Addresses are one of the ways that communication is made successful in the network. If we can use the post office analogy, you can imagine how difficult it would be if not impossible to send letters without a destination address or how difficult it would be if the recipient would not know who to reply to. The diagram below shows the various addresses that are used in communication over the network.

Summary

                               In this chapter, we have discussed how communication works over the layered model. We have looked at the TCP/IP and OSI reference models and how they define communication at each layer. We have also looked at the protocol data units and compared the two models. In the next chapter, we will look at the application layer.

                                                                             Post By – RamCruiseWalker

Different Types Of Router Memory, Introducion

Different Types Of Router Memory

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Different Types Of  Router Memory

 

ROM

               ROM is read-only memory available on a router’s processor board. The initial bootstrap software that runs on a Cisco router is usually stored in ROM. ROM also maintains instructions for   Power-on Self Test (POST) diagnostics. For ROM Software upgrades, the plugable chips on the motherboard should be replaced.
 
Flash Memory

                                         Flash memory is an Electronically Erasable and Re-Programmable memory chip. The Flash memory contains the full Operating System Image (IOS- Internetwork Operating System). This allows you to upgrade the OS without removing chips. Flash memory retains content when router is powered down or restarted.

RAM

            RAM is very fast memory that loses its information when the router is shutdown or restarted. On a router, RAM is used to hold running Cisco IOS Operating System, IOS system tables and buffers RAM is also used to store routing tables, keep ARP cache, Performs packet buffering (shared RAM). RAM Provides temporary memory for the router configuration file of the router while the router is powered on.

RAM Stores running Cisco IOS Operating System, Active program and operating system instructions, the Running Configuration File, ARP (Address Resolution Protocol) cache, routing tables and buffered IP Packets.

NVRAM (Non-volatile Random Access Memory)

              NVRAM is used to store the Startup Configuration File. This is the configuration file that IOS reads when the router boots up. It is extremely fast memory and retains its content when the router is restarted.

 

 Post By – RamCruiseWalker

 

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