TCP IP - Paiet/Tech-Journal-for-Everything GitHub Wiki

  • IP Address / Subnet Mask
    • IP Address: 192.168.0.1
    • Subnet Mask: 255.255.255.0
      • Class A - 255.0.0.0 - 16,777,214 Hosts
      • Class B - 255.255.0.0 - 65,534 Hosts
      • Class C - 255.255.255.0 - 254 Hosts
  • Private vs public IPs
    • Private IPs (RFC 1918)
      • 10.x.x.x
      • 172.16.x.x
      • 172.17.x.x...172.31.x.x
      • 192.168.0.x
      • 192.168.1.x...192.168.255.x
    • Public
      • Class A - 1.0.0.0 -> 126.255.255.255
      • Class B - 128.0.0.0 -> 191.255.255.255
      • Class C - 192.0.0.0 -> 223.255.255.255
  • IPv6
    • IPv6 vs IPv4
      • IPv4 Characteristics
        • 32 bit address
        • Around 4.3 Billion addresses
      • IPv6 Characteristics
        • 128 bit address
        • 3.4 x 10^38 addresses
        • Integrated IPSec
        • IP Mobility
        • Extensible Headers
  • UDP/TCP/ICMP
    • TCP
      • Transmission Control Protocol
      • Reliable transport mechanism
    • UDP
      • User Datagram Protocol
      • Best-effort transport mechanism
    • ICMP
      • Internet Control Management Protocol
      • Ping and other troubleshooting and status protocols
  • Port Number Lab
    1. Determine the IP for a server
    • dig itpro.tv
    1. Look for existing connections
    • ss -an | grep 192.124.249.2
    1. Browse to the web site from step 1
    2. Look for existing connections
    • ss -an | grep 192.124.249.2
  • Other examples
    • ftp.dell.com
    • towel.blinkenlights.nl

Common TCP/UDP Ports

Port Number | Protocol | TCP/UDP
----------------|-------------------|------------------- 20 | FTP | TCP
21 | FTP | TCP
22 | SSH | TCP
23 | TELNET | TCP
25 | SMTP | TCP
53 | DNS | TCP/UDP
80 | HTTP | TCP
110 | POP3 | TCP
119 | NNTP | TCP
123 | NTP | UDP
139 | NetBIOS | TCP/UDP
143 | IMAP | TCP
161 | SNMP | UDP
443 | HTTPS | TCP
465 | SMTP-SSL | TCP
993 | IMAPS | TCP
995 | POP3S | TCP