TCP/IP - Security Perspective
Upper Layers
CS-431
Dick Steflik
Application Layer Protocols
•Messaging Protocols
•SMTP, POP, MIME, IMAP, IM
•Telephony
•H.323, SIP (used with VoIP)
•RPC Based Protocols
•NIS, NFS, Andrew
•File Transfer Protocols
•TFTP, FTP, SMB
•Remote Login
•Telnet, rlogin, Ssh,
•Information Services
•Finger, whois, LDAP, WWW,NNTP
•Proprietary Protocols
•RealAudio, SQL’Net, VNC
SMTP
•Biggest problem is figuring out who a
piece of mail is really from
•Must use a higher level mechanism for trust or
privacy
•Most SMTP clients use sendmail which has
been a constant source of security problems
for years
MIME
•MIME headers could be hand crafted by
hacker to overwrite data
•MIME fragmentation could subvert virus
checkers ability to detevt embedded virus’
•Mailing of executable programs
POP
•Pretty insecure
•Passwords not secure, sent as clear text
•Exchanges are done as clear text
•Can be done over SSL/TLS
•Some UNIX systems POP runs as root until
user is authenticated and then switches to that
userid, never good to have servers running as
root (many sysadmins set up to run servers as
nobody)