Most modern networks have many resources that need to be protected. The reason is that most enterprises today implement network systems to provide information to users across the network in digital format rather than in another form, such as hard copies. Therefore, the number of resources that need to be protected increases significantly. The following list, by no means comprehensive, identifies network resources that need to be protected from various types of attacks: Netwo..
Cisco IOS Software Boot Sequences and the Configuration Register’
Cisco routers use the following basic process at boot time: 1. The router performs a power-on self-test (POST) to discover and verify the hardware. 2. The router loads and runs bootstrap code from ROM. 3. The router finds the Cisco IOS Software or other software and loads it. 4. The router finds the configuration file and loads it into the running configuration. Step 3 contains three major options for the type of software loaded into the router, as listed in Table 24-5. Table..
Switch port security monitors a port to restrict the number of MAC addresses associated with that port in the Layer 2 switching table. It can also enforce a restriction for only certain MAC addresses to be reachable out the port. To implement port security, the switch adds more logic to its normal process of examining incoming frames. Instead of automatically adding a Layer 2 switching table entry for the source MAC and port number, the switch considers the port security conf..
The core is the first place in your network where scaling issues will become apparent. This is because the core tends to combine the largest number of routes with the largest amount of traffic, taxing the routers to their limit. Using BGP in the core allows the routes in the core to separated into two parts: routes within the core and routes external to the core. The iBGP mesh carries the routes external to the core, while the IGP continues to carry just the routes within th..
Using SNMP to Extract Inventory Information from a List of Routers
The following Perl script extracts important router informationsuch as router name, physical location, contact name, and serial number from a list of routersand creates a report of this information. The script is intended to be run manually, and no arguments are required or expected. Here's some example output: Freebsd% ./inventory.pl Router Location ..
