Crypto for Network Protocols

CS 463 Lecture, Dr. Lawlor

Purpose	Insecure	Secure	Built on	Popularity
Web	http	https	TLS/SSL, X.509 PKI	Common
Files	ftp / nfs	scp	rsa, aes-128-ctr	Common
Shell	telnet / rsh	ssh	same	Common
Domain names	DNS	DNSSEC	hash+signature	Coming soon
Single sign on	LDAP (v2)	Kerberos	central server	Declining
Basic connectivity	IP	IPsec	IKE	Coming soon

A disturbing number of commonly used network protocols use exactly zero crypto. This makes them susceptible to both information leakage and a variety of man in the middle attacks.

DHCP (Dynamic Host Configuration Protocol) is how your machine finds its own IP address and DNS server names. It's implemented as a broadcast to UDP port 67 asking for an IP address. It's vulnerable to a rogue DHCP server sending out bad IP addresses or DNS servers, for example to redirect IP traffic or DNS requests to a bad server.
ARP (Address Resolution Protocol) is how your machine finds the ethernet address for an IP address, basically by broadcasting "Who has 10.0.0.1?". It's vulnerable to "spoofing" attacks, typically used to transparently redirect traffic to an attacker's machine. Luckily ARB spoofing is fairly easy to for an intrusion detection system to detect.
BGP (Border Gateway Protocol) updates subnet routing information on the internet's core routers. As you've now come to expect, it's totally unencrypted and subject to a variety of attacks.