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Network Security Tips

VRRP Configuration(virtual router redundancy protocol)

VRRP or virtual router redundancy protocol provides router or switch interfaces failover and failback facility for seamless operation of a network. VRRP almost similar to HSRP in terms of operations and functions, but with a few added features such as VRRP supports up to 255 groups.

Just like HSRP, VRRP also support a number of routers to form a virtual group which acts like a single router. Every access request send to the virtual IP is responded regardless of the fact which router is in active mode. In VRRP only one router will remain active to forward all the traffic send to its Virtual IP address, and there will be one standby router and several candidate routers. In case of the active router failure or its interface failure, the role of active router will be shifted to the sandy router. And when the active router will be back in operation it will resume its responsibility as an active router.  [Read more…] about VRRP Configuration(virtual router redundancy protocol)

GLBP-Gateway Load Balancing Protocol Configuration

What is GLBP: Gateway Load balancing protocol is a Cisco proprietary protocol for both redundancy and load balancing in Cisco switches and routers. Although VRRP or HSRP provides a network link redundancy to router traffic in a or a number of routers in case of failure to the main active routes, but they do not allow to fully utilizing the available network resources. GLBP provides a single virtual IP address and a number of virtual MAC addresses to a GLBP group to make sure all the available networking resources are fully utilize to reduce the high traffic to a single device and at the same time it reroute traffic automatically in the event of a network device or port failure.       [Read more…] about GLBP-Gateway Load Balancing Protocol Configuration

Cisco VPN Configuration in IOS Routers

How to Configure VPN in Cisco Routers

Virtual private network can be configured with most of the Cisco routers( 800 to 7500 series) with IOS version 12 or higher.VPN can be implemented in a number of ways–with various level of security measures and configuration. To determine the right VPN configuration for your network, you need to have a solid understanding in cryptographic system and encryption algorithm.Besides, one needs to know which type of VPN is suitable for remote clients  and which type of VPN  is used to create secure site-to-site connection. This article explains the necessary steps with configuration script to setup VPN in Cisco routers. This configuration can be simulated in Cisco packet tracer software as well.  [Read more…] about Cisco VPN Configuration in IOS Routers

Access Control List Configuration on Cisco Router

What is ACL: Access control list or ACLs are a set of if-then rules set on a router to allow or deny a specific group of IP to send or receive traffic from your network into another network.

When you apply an ACL to a route interface  for incoming traffic then every incoming packets will be compared with your ACL first, if a match is found then either permit or deny action will take place according to your configuration of the ACL. If there are more than one ACL and if there is no match after comparing the incoming packets with the first ACL, then the second ACL will be matched and so on. Remember there is an implicit deny after an ACL. That is why after permit or denies any IP or IP range you must add the command: access-list ip permit any any.

For example in your network you want that no computer or devices from 172.16.0.0 network can send traffic to your network. To implement this rule you need to write and ACL that will tell your router to discard all the traffic from 172.16.0.0. Now, let see how to implement this ACL into a router.

Rourter#configure terminal

Router(config)# access-list 10 deny ip 172.16.0.0 0.0.255.255

Router (config) #access-list 10 permits ip any any

[Read more…] about Access Control List Configuration on Cisco Router

Screening Router Security Test

Much small-scale business does not use firewall as their first line of defense any web attacks to their internal network. Instead, they use a router between the Internet and Internal network to control incoming and outgoing traffic flow- this type of use of router is known as screening router. In fact, configuring ACLs inside a router can be a viable and effective solution to deny any incoming malicious packets to your LAN. If you have to test one such type of network router that is used a screening router, then you have to identify the type of router and its features. List all the ACL policy and the types of data packets that are permitted to enter your network. What are the router responses to various types of incoming traffic? Finally list all the live systems The following are the list of activity the you have to perform to test a screening router

1. Identify router type

2. List NAT, if there is any

3. Use TTL setting test by using port scanning

4. Test all the ACLs in the router

5. Verify if the address spoofing is being detected by the router

6. Test inverse scanning

7. If the router is filtering local traffic(egress filtering)

8. How the router is handling small size packets

9. How over-sized packets are being handled in the router

10. How router responding to overlapped packets. Normally overlapped fragments are used in TEARDROP attack.