Network Cheat Sheet - Quick
IPs / Subnets
Classes
- CIDR - Classless Inter-Domain Routing - basically use any netmask
| Class | Bits | Network | Broadcast | Netmask | Prefix Size |
|---|---|---|---|---|---|
| Class A | 0— | 0.0.0.0 | 127.255.255.255 | 255.0.0.0 | /8 |
| Class B | 10– | 128.0.0.0 | 191.255.255.255 | 255.255.0.0 | /16 |
| Class C | 110- | 192.0.0.0 | 223.255.255.255 | 255.255.255.0 | /24 |
| Class D | 1110 | 224.0.0.0 | 239.255.255.255 | ||
| Class E | 1111 | 240.0.0.0 | 255.255.255.255 |
- Class A - first 1 octet is network
- Class B - first 2 octets are network
- Class C - first 3 octets are network
- Class D - multi-cast
- Class E - experimental / future use
Private Ranges
| 10.0.0.0 | 10.255.255.255 | class A - Private |
| 172.16.0.0 | 172.31.255.255 | class B - Private |
| 192.168.0.0 | 192.168.255.255 | class C - Private |
| 127.0.0.0 | 127.255.255.255 | loopback range |
- Broadcast address - all bits set in host section like this: 172.16.255.255
- Network address - no bits set in host section like this: 172.16.0.0
Common Ports
- 1024 - ports below this are privileged
- 65535 - max port
| 20/21 | FTP |
| 22 | SSH |
| 23 | Telnet |
| 25 | SMTP |
| 53 | DNS |
| 67 | DHCP Server (UDP) |
| 68 | DHCP Client (UDP) |
| 69 | TFTP (UDP) |
| 70 | Gopher |
| 79 | Finger |
| 80 | HTTP |
| 110 | POP3 |
| 119 | NNTP |
| 123 | NTP |
| 143 | IMAP |
| 161 | SNMP |
| 179 | BGP |
| 194 | IRC |
| 389 | LDAP |
| 443 | HTTPS |
| 500 | ISAKMP |
| 8080 | Web |
| 3306 | MySQL |
| 3389 | RDP |
| 5800 | VNC |
| 5900 | VNC |