CS445 Slides 5

Remote Access Protocols

rlogin, telnet, ssh

telnet

port 23

interactive raw tcp sessions

whats wrong with telnet?

doesnt encrypt data

Risks of remote access protocols

• data travels in cleartext

• intermdiate hosts can hijack sessions

• authentication based on IP addy

  • auth based on reusable passwords

SSH

secure encrypted communication between 2 untrusted hosts over an insecure network

port 22

application layer

SSH Steps

• tcp connection string

• ssh version string exchange

• algo negotitation

• ssh key exchange

• server auth

• ssh data exchange

  • termination of tcp connection

SMTP

Simple mail transfar protocol

tcp port 25

supports only 7 bit ascii

MIME

Multipurpose internet Mail Extensions

Emails can now include images, sounds, video, and html

S/MIME

Secure MIME

A way to send and receive secure MIME data

What type of encryption does S/MIME use?

Symmetric key cryptography and public key cryptography