TCP/IP Protocols

At the transport layer, most homelab traffic reduces to a simple tradeoff: reliability or speed. TCP and UDP make different choices, and your applications inherit those choices.

IP Addresses

IPv4 Format: 192.168.1.20
|- 4 octets, each 0-255
`- Total: 4.3 billion addresses (now running out)
 
Private ranges (not routable on the internet):
|- 192.168.0.0 - 192.168.255.255  <- your homelab network
|- 10.0.0.0 - 10.255.255.255
`- 172.16.0.0 - 172.31.255.255
 
Public IP: assigned by your ISP, unique on the internet
`- Changes on router reboot unless you pay for a static IP

TCP

TCP guarantees that data arrives in order and that lost packets are retransmitted. It establishes a connection first, then starts sending data.

Client                  Server
  |-- SYN ------------> |    "I want to connect"
  |<- SYN-ACK --------- |    "OK, ready"
  |-- ACK ------------> |    "Great, starting"
  |                      |
  |=== data flowing ====|

Used by HTTP, HTTPS, SSH, and databases - anything where missing or reordered data is unacceptable.

UDP

UDP skips the handshake and sends packets immediately. That makes it faster and simpler, but packets can be lost or arrive out of order.

Used by DNS queries, video streaming, VoIP, and gaming - situations where speed matters more than perfect delivery.

TCP vs UDP

If you are debugging a system, this matters because TCP failures usually look like connection resets, retries, or timeouts, while UDP failures often look like intermittent packet loss or missing responses.