Router

Reset Cisco Router password

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Reset Cisco Router password:

Today i will discuss how to reset Cisco Router password. so follow bellow steps………..

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Step-1.  Reboot your router first, when it rebooting attempt to break into ROM Monitor (ROMmon) by issuing the break sequence (usually Ctrl and break from the Hyperterminal) from a console connection. Refer to: Cisco Standard Break Key Combinations You should see this ROMmon prompt:

rommon 1>

Step-2.  Change the configure register value to ignore the startup configuration by issuing the confreg command, as shown in this example:

rommon 1> confreg 0x2142

Step-3.  To reload the router, issue the reset command, as shown in this example:

rommon 2> reset

Reset Cisco Router password
Reset Cisco Router password

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Cisco Router factory-default

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Cisco Router factory-default:

Today i will discuss how to do Cisco Router factory-default or initial configuration mode. we configure it two way, “Erase nvram“ and “erase startup-config”, So lets follow bellow procedure………..[boxads]

#.To erase the configuration file, use erase nvram: command.

Router> en
Router#erase nvram:

Reload the router by reload command.

Router# reload

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Network Security Attacks and Defence

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Network Security Attacks and Defence

Today I will discuss about Network Security Attacks and Defence. Network security involves the authorization of access to data in a network, which is controlled by the network administrator.

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Users choose or are assigned an ID and password or other authenticating information that allows them access to information and programs within their authority. Network security covers a variety of computer networks, both public and private, that are used in everyday jobs conducting transactions and communications among businesses, government agencies and individuals. Networks can be private, such as within a company, and others which might be open to public access. Network security is involved in organizations, enterprises, and other types of institutions. It does as its title explains: It secures the network, as well as protecting and overseeing operations being done. The most common and simple way of protecting a network resource is by assigning it a unique name and a corresponding password.

Types of attacks include:

Active:
1.  Denial-of-service attack (DoS)
2.  Spoofing
3.  Man in the middle
4.  ARP poisoning
5.  DNS Spoofing
6.  Smurf attack
7.  Buffer overflow
8.  Heap overflow
9.  Format string attack
10.  SQL injection
11. Cyber attack

Passive:
1. Network
a. Wiretapping
b. Port scanner
c. Idle scan

Denial-of-Service Attack (DoS)

Denial of Service (DoS) attacks are among the most feared threats in today’s cybersecurity landscape. Difficult to defend against and potentially costly, DoS attacks can cause outages of web sites and network services for organizations large and small. DoS attacks can also be lucrative for criminals, some of whom use these attacks to shake down businesses for anywhere from thousands to millions of dollars.

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HSRP Tuning Example

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HSRP Tuning Example

Today I will discuss about HSRP Tuning. As you see in the article “HSRP (Hot Standby Router Protocol)”, it is quite simple configure Hot Standby Router Protocol. [boxads]
Some cases require a custom configuration, using priority, track, preempt etc…and these are:

  • The standby preempt interface configuration command allows the router to become the active router when its priority is higher than all other HSRP-configured routers in this Hot Standby group. The configurations of both routers include this command so that each router can be the standby router for the other router. If you do not use the standby preempt command in the configuration for a router, that router cannot become the active router.
  • The standby priority interface configuration command sets the router’s HSRP priority (the default priority is 100).
  • The standby timers interface configuration command sets the interval in seconds between hello messages (called the hello time) to five seconds and sets the duration in seconds that a router waits before it declares the active router to be down (called the hold time) to eight seconds. (The defaults are three and 10 seconds, respectively.) If you decide to modify the default values, you must configure each router to use the same hello time and hold time.
  • The standby track command allows you to specify another interface on the router for the HSRP process to monitor in order to alter the HSRP priority for a given group. If the line protocol of the specified interface goes down, the HSRP priority is reduced. This means that another HSRP router with higher priority can become the active router if that router has standby preempt enabled.
  • The standby authentication interface configuration command establishes an authentication string whose value is an unencrypted eight-character string that is incorporated in each HSRP multicast message. This command is optional. If you choose to use it, each HSRP-configured router in the group should use the same string so that each router can authenticate the source of the HSRP messages that it receives.

Suppose to have this physical configuration:

HSRP Tuning Example
HSRP Tuning Example

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HSRP (Hot Standby Router Protocol)

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HSRP (Hot Standby Router Protocol)

The HSRP (Hot Standby Router Protocol) is a Cisco proprietary first-hop redundancy protocol (FHRP) designed to allow for transparent fail-over of the first-hop IP router, and has been described in detail in RFC 2281.

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HSRP provides high network availability by providing first-hop routing redundancy for IP hosts on Ethernet, Fiber Distributed Data Interface (FDDI), Bridge-Group Virtual Interface (BVI), LAN Emulation (LANE), or Token Ring networks configured with a default gateway IP address. HSRP is used in a group of routers for selecting an active router and a standby router. In a group of router interfaces, the active router is the router of choice for routing packets; the standby router is the router that takes over when the active router fails or when preset conditions are met. HSRP active and standby routers send hello messages to the multicast address 224.0.0.2 using UDP port 1985.

The virtual router is simply an IP and MAC address pair that end devices have configured as their default gateway. The active router processes all packets and frames sent to the virtual router address. The virtual router does not process physical frames and exists in software only. The active router physically forwards packets sent to the MAC address of the virtual router. The virtual router MAC address is a well know mac-address and it is 0000.0c07.acxx, where xx is the HSRP group member. For example, if the group is 20 the virtual MAC address is 0000.0c07.ac14 (remember that the number in the mac address is expressed in HEX!!!).

When the active router fails, the other HSRP routers stop seeing hello messages from the active router. So, the standby router will be the new active router and, if possible, a new standby router will be elected. Because the new active router assumes both the IP and MAC addresses of the virtual router, the end stations see no disruption in service. The end-user stations continue to send packets to the virtual router MAC address, and the new active router delivers the packets to the destination.

HSRP has 2 timers:

  • Hello interval time: Interval between successive HSRP hello messages from given router. Default is 3 seconds.
  • Hold interval time: Interval between the receipt of a hello message and the presumption that the sending router has failed. Default is 10 seconds.
HSRP (Hot Standby Router Protocol)
HSRP (Hot Standby Router Protocol)

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VRRP Tutorial (Virtual Router Redundancy Protocol)

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VRRP Tutorial (Virtual Router Redundancy Protocol)

Today i will discuss about VRRP Tutorial, VRRP stands for Virtual Router Redundancy Protocol. It is a FHRP: First Hop Redundancy Protocol, which means they allow you to configure more than one physical router but it can still be seen as a single router.
First Hop means that any packet traveling out the network has its gateway as its first hop. It is protocol used for Gateway redundancy. [boxads]

–         It is similar to the HSRP protocol by Cisco
–         It is an open standard redundancy protocol i.e. can be used between different vendors
–         Was created by the IETF in 1999 and became industry standard
–         Faster than HSRP
–         The hello time is of 1 second
–         The Dead timer or Hold timer is of 3 seconds
–         The Active / Standby of HSRP are known as Master / Backup in VRRP
–         The Standby Group of HSRP is known as VRRP Group
–         If we use the real IP address then that router becomes the master
–         In case a Virtual IP address is used, the router with the highest priority is considered Master
–         VRRP messages are used to inform group members its status by the VRRP master
–         The virtual MAC address by default is 0000.5e00.01xx, where  xx means the hexadecimal group number
–         The Hellos in VRRP are sent to 224.0.0.18 multicast address
–         Default priority used is 100
–         The VRRP group number range is from 0 to 255
–         In VRRP the priorities range is from 1 to 254 ( 100 is default)
–         In VRRP the routers are configured to preempt the current master router by default if the priority is greater.
–         Advertisements in VRRP are sent to the multicast destination address 224.0.0.18 (VRRP), using IP protocol 112.
–         In VRRP , router Role, we can have one Master router and one or more Backup routers
–         By default preempt is on in VRRP which means that if a router that was master goes down, it loses master-ship but if it comes up again, it becomes master without any config changes or intervention.
–          Does not support IPv6
Consider the following diagram, we have Router0 and Router1 configured with the VRRP configuration.

VRRP
VRRP

The Virtual IP (VIP) to be used is 10.10.10.10

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