This lecture explores how the naming services DNS and ARP are vulnerable
to spoofing attacks. It also considers how we access remote systems,
highlights the weaknesses of old tools such as
discusses the effectiveness of SSH as a drop-in replacement for those
tools. Finally, it considers the inherent lack of security in the email
protocols SMTP, POP3 and IMAP, and examines how TLS has been used to
add security to them.