Other Applications of Policy Routing

One practical application of policy routing is its use with firewalls. Firewalls are devices that apply security requirements to traffic. Firewall implementations include packet filtering, authentication, and encryption. Depending on the network setup, administrators might want to direct some or all incoming (or outgoing) traffic toward a firewall device, as shown in Figure 8-9. Figure 8-9. Incoming or Outgoing Traffic Can Be Routed to a Firewall   An applicable situati..

Determining All Subnets of a Network—Binary

Another common question, typically simply a portion of a more challenging question on the CCIE written exam, relates to finding all subnets of a network. The base underlying question might be as follows: Given a particular class A, B, or C network, and a mask/prefix length used on all subnets of that network, what are the actual subnet numbers? The answers can be found using binary or using a simple decimal algorithm. This section first shows how to answer the question using..

Vulnerabilities, Attacks, and Common Exploits

This section covers some of the vulnerabilities in TCP/IP and the tools used to exploit IP networks. TCP/IP is an open standard protocol, which means that both network administrators and intruders are aware of the TCP/IP architecture and vulnerabilities. Note There are a number of network vulnerabilities, such as insufficient password protection, lack of authentication mechanisms, use of unprotected routing protocols, and firewall holes. This section concentrates on TCP/IP..

Using SNMP to Modify a Router's Running Configuration

To upload or download a current copy of your router's configuration file to a TFTP server via SNMP, you have to first configure the router for read-write SNMP access: Router#configure terminal Enter configuration commands, one per line.  End with CNTL/Z. Router(config)#snmp-server community ORARW rw Router(config)#end To download the current configuration file, you will need to create an empty file on your TFTP server. In this case, we assume a Unix server, although TF..

Removing Private ASNs from the AS Path

You have to be extremely careful that any unregistered ASNs that you may be using don't propagate into the public Internet. In this example, the router has a BGP connection to an ISP, which uses ASN 1. Our router uses ASN 2 and connects to another router with an unregistered ASN, 65500: Router1#configure terminal Enter configuration commands, one per line.  End with CNTL/Z. Router1(config)#interface Serial0 Router1(config-if)#description connection to ISP #1, ASN 1 Rou..