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Look after yourself!

CITS3002 Computer Networks - Tutorial 6 (last tutorial this semester)

1. We know that distinct client and server programs can establish a connection between themselves, even when both are running on the same host (using 'localhost').

   Would it be desirable for a running process, acting as client, to make a TCP/IP connection to itself, acting as a server?

   Why might it be difficult to establish the connection? Are their any solutions?
   
   

2. Everyone is all too familiar with spam-email. According to DataProt 56.5% of all emails were spam in 2022. Most of these emails contained malicious links or attachments designed to infect computers with malware or steal sensitive data.
   Not only is spam annoying to receive, it consumes network and computer system resources at virtually no cost to the sender. While the Internet remains a "receiver-pays" environment, and while we generally wish to receive email from "reasonable" sources, effort must be expended by the receiver of spam to reduce it.
   Despite the long known advantages of the basic cryptographic building blocks, such as message digests, digital signatures, and digital certificates, none have been effectively employed in eliminating spam. In particular, we remain a long way from the day when all email senders and receivers can authenticate their exchanges using public-key cryptography. Moreover, significant changes to the Internet charging structures, such as "receiver pays, except for email" are probably intractable.
   Devise a scheme, employing one or more of the basic cryptographic building blocks to thwart the senders of spam (implementation is left as an exercise).