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IPSec and Firewalls. Section 8.6.1, 8.6.2. IPSec. Internet Protocol Security RFC 2401 (4301) security in the network layer authentication secrecy what is the difference? build a Security Association between two computers a shared key is setup
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IPSec and Firewalls Section 8.6.1, 8.6.2
IPSec • Internet Protocol Security • RFC 2401 (4301) • security in the network layer • authentication • secrecy • what is the difference? • build a Security Association between two computers • a shared key is setup • Internet Key Exchange RFC 4306 (version 2)
Authentication Header When might this cause problems? What does this guarantee? Tanenbaum, p 774, Figure 8-27
Encapsulating Security Payload Header Tanenbaum, p 775, Figure 8-28
Encapsulating Security Payload Header Tanenbaum, p 775, Figure 8-28
Firewall/Packet Filter • Inspect each packet in the kernel • Filter before giving to an application • Linux – netfilter/iptables • http://netfilter.org/ • ipchains is obsolete • FreeBSD & Max OSX – ipfw • http://www.freebsd-howto.com/HOWTO/Ipfw-HOWTO • Windows – built in firewall • many commercial products
iptables # Allow HTTP iptables -A tcp_inbound -p TCP -s 0/0 --destination-port 80 -j ACCEPT # Allow HTTP from zeus.cs.pacificu.edu iptables -A tcp_inbound -p TCP -s zeus.cs.pacificu.edu --destination-port 80 -j ACCEPT # DisAllow HTTP iptables -A tcp_inbound -p TCP -s 0/0 --destination-port 80 -j DENY