TCP/IP Protocols

TCP Port Numbers

21 FTP
23 Telnet
25 SMTP
80 HTTP
110 POP3
443 HTTPS

UDP Port Numbers
69 TFTP
520 RIP

TCP/UDP Common Ports
53 DNS
161 SNMP
531 AOL Instant Messenger IRC

OSI Model Layers

1. Application Layer
2. Presentation Layer
3. Session Layer
4. Transport Layer
5. Network Layer
6. Data Link Layer
7. Physical Layer

Reduced Layers

1. Application Layer
2. Transmission Layer
3. Internet Layer
4. Data Link Layer
5. Physical Layer

TCP: Three-way handshake

=> SYN Seq=0

<= SYN, ACK Seq=0 Ack=1

=> ACK Seq=1 ACK=1

(response ACK = received Seq+1)