tailieunhanh - Hacking - Firewalls And Networks How To Hack Into Remote Computers

Gaining access and securing the gateway | AR RT P T PA PA RT P T A R R A T P P T A R R A T P P T A R R A T P P T A R R A T P P T A R R A T IIP Gaining Access and Securing the Gateway 6 IP Spoofing and Sniffing .257 7 How to Build a Firewall .317 8 SATAN and the Internet Inferno 429 9 Kerberos .535 p1vPHCP/tr2 Internet Security Pro Ref 557-7 dc 1-23-96 Parts LP#2 IP Spoofing and Sniffing 257 HAPTER R C CH TE AP P T A E H R C C R H E A T P P T A E R H C C H R E A T P P T A E R H C C H R E A T 6P IP Spoofing and Sniffing S niffing and spoofing are security threats that target the lower layers of the networking infrastructure supporting applications that use the Internet. Users do not interact directly with these lower layers and are typically completely unaware that they exist. Without a deliber- ate consideration of these threats, it is impossible to build effective security into the higher levels. Sniffing is a passive security attack in which a machine separate from the intended destination reads data on a network. The term “sniffing” comes from the notion of “sniffing the ether” in an Ethernet network and is a bad pun on the two meanings of the word “ether.” Passive security attacks are those that do not alter the normal flow of data on a communication link or inject data into the link. p1vPHCP/nhb1 Internet Security Pro Ref 577-7 Gina 1-27-96 CH06 LP#3 258 Part II: Gaining Access and Securing the Gateway Spoofing is an active security attack in which one machine on the network masquerades as a different machine. As an active attack, it disrupts the normal flow of data and may involve injecting data into the communications link between other machines. This masquerade aims to fool other machines on the network into accepting the impostor as an original, either to lure the .