History of home networking 2

Last time: level 5 home subnetwork

Home subnet:

ISP:

The reddit:

If we live in the world of IPv6 (each hosts get assigned a unique IPv6 address):

• As long as PC1 (18.1.14.4) and the reddit (151.2.3.9) stores the source and dst IP addresses of the TCP Connection in their socket, the TCP connection can be done
  • PC1: 18.1.14.4: 5678 ← —> 151.3.2.4:443: reddit
• DNS + DHCP + switch + router + modem used to be independent parts, but now they goes in to a “home router” you can buy from a shop

Level 6: Proxy server/ jump host / bastion / socks5

Each subnets have a local range of IPv4 addresses

The computer relays the bytes between TCP connection 1 and TCP connection 2.

But this is annoying for asking every new PC to also set up the proxy

Level 7: Transparent Proxy

The PC does not know the existence of the proxy

And the proxy computer acts as if it is the reddit server in the home subnet, and relay the connection out with its own public IP address

Level 8: network address/port translation ( NAT )

For the proxy, it no longer reconstruct the byte stream, but only do translation on the IP address and port to appear in the public network