One of the most well-known network intrusion attacks was conducted by Kevin Metnick on Christmas Day 1994. The attack resulted in a well-documented story that ended with Metnick's arrest. Tsutomu Shimomura was the computer security scientist whose computers were hacked and who finally helped bring the whole episode to a conclusion. This case study covers the attack that Metnick launched on Shimomura's computers and analyzes how an intrusion-detection mechanism could have giv..
The link-state update packet, OSPF packet type 4, is sent in response to the link-state request packet and implements the flooding of LSAs. The link-state update packet carries a collection of LSAs one hop from its origin. Several LSAs can be included in a single update. Each LSA must be acknowledged. In response to the link-state update, a link-state acknowledgment packet is sent to multicast addresses on the networks that support multicast. If retransmission o..
As if 100 Mbps is not enough, yet another higher bandwidth technology was unleashed on the industry in June of 1998. Gigabit Ethernet (IEEE 802.3z) specifies operations at 1000 Mbps, another tenfold bandwidth improvement. We discussed earlier how stations are hard-pressed to fully utilize 100 Mbps Ethernet. Why then do we need a Gigabit bandwidth technology? Gigabit Ethernet proponents expect to find it as either a backbone technology or as a pipe into very high speed file se..
Integrated Services Digital Network
ISDN is a digital service that enables network users to send and receive data, voice, and video transmissions over a network. ISDN offers a variety of link speeds, ranging from 64 kbps to 2.048 Mbps (including a signaling channel of 64 kbps). With the advent of DSL and cable, ISDN may not be a viable network solution for anything other than a backup link, because of the expense involved. Basic Rate and Primary Rate Interfaces ISDN can be supplied by a carrier in two main fo..
Preventing Unwanted Neighbors Using Passive
Interfaces When an EIGRP network configuration subcommand matches an interface, EIGRP on that router does two things: Step 1. Attempts to find potential EIGRP neighbors by sending Hellos to the 224.0.0.10 multicast address Step 2. Advertises about the subnet connected to that interface In some cases, however, no legitimate EIGRP neighbors may exist off an interface. For example, consider the small internetwork of Figure 1-1, with three routers, and with only one router connec..
