LINUX:In 1969 AT&T made a decision to withdraw Multics and go with GECOS (General Electric Comprehensive Operating Supervisor / System), with AT & T in Bells Lab when Multics was withdrawn some of the programmers named Ken Thompson and Dennis Ritchie decided to rewrite operating system in order to support low cost computer..To Know More



    MICROSOFT:Microsoft was established to develop and sell BASIC interpreters for the Altair 8800. It rose to dominate the home computer operating system market with MS-DOS in the mid-1980s,followed by the Microsoft Windows line of operating systems. To Know More



    CISCO:During the early 1980s, there was a married couple namely Len and Sandy Bosack who used to work in two different departments of computer located in Stanford University. This couple was facing problem in making their computers communicate with each other To Know More



Password resetting on cisco router.

Note: After doing all these steps you will lose your all configuration so make sure you have backup of your configuration.

Start the router and interrupt the router boot process by pressing Ctrl+break OR Ctrl+pause key after performing this step you will see the following prompt on router. 


The configuration register can be used to change router behavior in several ways, such as:
  • how the router boots (into ROMmon, NetBoot)
  • options while booting (ignore configuration, disable boot messages)
  • console speed (baud rate for a terminal emulation session)

SSH configuration

Secure Shell (SSH) is a protocol which provides a secure remote access connection to network devices. Communication between the client and server is encrypted in both SSH version 1 and SSH version 2.


Telnet configuration

We will use this topology to configure telnet, there are two routers in topology R1 and R2. we will configure telnet on R2 and we will use one of the Laptop which is connected to R1 network, but actually you can access R2 from any Laptop/Location after configuring telnet.

I have already configured RIPv2 on both router so the network is fully converged.

Now lets see the commands to configure telnet on R2.

Router security

Password setup on router OR switch

same topology we will use for configuring TELNET and SSH. Now lets see how to setup password on the router.

These are the commands to setup password on router OR switch.

R1#configure terminal
R1(config)#enable ?
                Password :  Assign the privileged level password

                Secret :   Assign the privileged level secret

Inter Vlan Routing

Router on a stick

Now we will configure inter-vlan routing for which we will use our previous topology.
previous topology -
i have added one router into this topology to configure Router on a stick.
router's f0/0 is connected to Switch_1 on f0/20.

Commands to configure router for inter-vlan routing.



What is VLAN ?

AVLAN is a group of end stations with a common set of requirements, independent of their physical location. A VLAN has the same attributes as a physical LAN, except that it lets you group end stations even when they are not physically located on the same LAN segment. A VLAN also lets you group port on switch so that you can limit unicast, multicast, and broadcast traffic flooding. Flooded traffic that originates from a particular VLAN floods only to the ports belonging to that VLAN. VLAN trunks with IEEE 802.1Q tagging facilitate interswitch communication with multiple VLANs. Cisco catalyst switches feature VLAN Trunking Protocol (VTP) to simplify management of VLANs across multiple switches.

Understanding VLANs

Issue in a poorly designed network

· Large broadcast domain

· Large amount of unknown MAC unicast traffic

Congfiguring VLANs

To configure VLAN we will use the following topology
Topology overview: Laptop_1, Laptop_2, Laptop_3 and Laptop_4 are connected to Switch_1 on port f0/6, f0/7, f0/8 and f0/9 respectively.
f0/5 on Switch_1 which is connected to Switch_2 on f0/13 would be the trunk port.
Laptop_5, Laptop_6, Laptop_7 and Laptop_8 are connected to Switch_2 on port f0/9, f0/10, f0/11 and f0/12 respectively.

configuring frame relay switch in gns3

FRM Router which is in middle working as a frame-relay switch

Frame-relay Switch Configuration Commands

FRS#configure terminal

FRS(config)#frame-relay switching

FRS(config)#interface serial 1/0

A device attached to the system is not functioning. Error status: 0x0000001.


A device attached to the system is not functioning.  Error status: 0x0000001.  Please shutdown this system and reboot into Directory Services Restore Mode, check the event log for more detailed information.

These steps apply to a 2008 R2 Core machine which is the only domain controller in the domain which had no backups.  The symptoms are the server failed to boot due to a BDS error.  The server has a BSD error indicating "Directory Services could not start because of the following error:  A device attached to the system is not functioning.  Error status: 0x0000001.  Please shutdown this system and reboot into Directory Services Restore Mode, check the event log for more detailed information."  Here are the steps I used to restore the DC.

1.  Restart the server and press F8 key, select Directory Services restore mode.

Installing and Configuring SSL under Windows

Installing and Configuring SSL under Windows

Installing and Configuring SSL under Windows require the following Three steps.

1. Check the system and software requirement

2. Setting Up Digital Certificates for SSL under Windows

3. Converting between PEM and DER File Formats for SSL


SSL under Windows: System and Software Requirements

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