Ports and services to know about

Let's consider the ports and services you will want to be familiar with:

• Most of the DNS information that goes across the network is going to be using port 53.
• Simple Mail Transfer Protocol (SMTP) typically uses port 25.
• Microsoft RPC endpoints use TCP 135.
• The global catalog service, which is a stripped-down version of Active Directory that users and applications take advantage of all the time, queries port 3286.
• The NetBIOS naming service, which is typically the computer name to an IP address, uses port 137, both TCP and UDP.
• LDAP or LDP is the protocol used by Active Directory, Open Directory, and all the different directory services out there. It uses TCP and UDP port 389.
• SMB, which is our server message block over NetBIOS, is what creates shared resources or shared folders, and it uses TCP 139 to make connections.
• We also have SNMP, which uses UDP 161. The other SMB technology that it can use is...