SUMMARY

In this chapter, we discussed how devices are detected on the network using scanning and tracerouting techniques. Identifying these devices on your network proved simple and was combined with banner grabbing , operating system identification, and unique identification. We discussed the perils of poorly configured SNMP and default community names . In addition, we covered the various backdoor accounts built into many of today's network devices. We discussed the difference between shared and switched network media and demonstrated ways that hackers listen for telnet and SNMP network traffic to gain access to your network infrastructure with packet analyzers such as dsniff and linsniff. We also discussed how attackers use ARP to capture packets on a switched network and how they use SNMP and routing protocol hacking tools to update routing tables to enable session sniffing in order to trick users into giving up information. Finally, we discussed the dangers and perils surrounding SNMP-like vulnerabilities.

Reviewing network security on a layer-by-layer basis, we covered specific vulnerabilities and how unsecured layered network resources can lead to a total compromise of data and integrity. Only with proper network hardening, monitoring, and updating can we use our networks in a dependable fashion.