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Wednesday, July 18, 2018

Common Ports

  • 20-21 - FTP (File Transfer Protocol)
  • 22 - SSH (Secure SHell)
  • 23 - Telnet
  • 25 - SMTP (Simple Mail Transport Protocol)
  • 49 - TACACS
  • 53 - DNS (Domain Name Services)
  • 67-68 - DHCP (UDP)
  • 69 - TFTP (UDP)
  • 80 - HTTP (Hyper Text Transfer Protocol)
  • 110 - POP3
  • 111 - RPC
  • 123 - NTP (UDP)
  • 135 - Windows RPC
  • 137-138 - NetBIOS
  • 139 - SMB
  • 143 - IMAP
  • 161 - SNMP (UDP)
  • 179 - BGP
  • 201 - AppleTalk
  • 389 - LDAP
  • 443 - HTTPS
  • 445 - SMB
  • 514 - Syslog
  • 520 - RIP
  • 546-547 - DHCPv6
  • 902 - VMWare
  • 1194 - VPN
  • 1433-1434 - MSSQL
  • 1521 - Oracle
  • 3306 - MySQL
  • 3389 - RDP (Remote Desktop Protocol)
  • 5432 - Postgres
  • 5900 - VNC
  • 6667 - IRC
  • 9001 - TOR
  • 9100 - JetDirect​

Here is a nice chart of common ports: http://ciscotut.com/pdf/common_ports.pdf

Classful IP4 Ranges

  • Class A: 0.0.0.0—127.255.255.255
  • Class B: 128.0.0.0—191.255.255.255
  • Class C: 192.0.0.0—223.255.255.255
  • Class D: 224.0.0.0—239.255.255.255
  • Class E: 240.0.0.0—255.255.255.255

The following ranges are reserved:

  • 10.0.0.0—10.255.255.255
  • 127.0.0.0—127.255.255.255
  • 172.16.0.0—172.31.255.255
  • 192.168.0.0—192.168.255.255

Subnetting:

An address like 192.168.3.27 with a subnet mask of 255.255.255.0 can be written 192.168.3.27/24. This is the full Class C range.

The range can be split into smaller subnets with different subnet masks. E.g. 255.255.255.240 is the same as /28 and 255.255.255.192 is the same as /26.

To calculate what range a given IP falls in, do the following:

  • Let's assume the example of 192.168.3.27/28
  • /28 is the 255.255.255.240 netmask
  • 256 - 240 = 16, so this is the subnet range
  • Alternatively, 32 - 28 = 4 and 2**4 is 16 (easier method!)
  • So the subnets are 192.168.3.0, 192.168.3.16, 192.168.3.32, and so on
  • You can see that our example falls in the 2nd subnet range

“If I had eight hours to chop down a tree, I'd spend the first six of them sharpening my axe.”

Abraham Lincoln

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