How to Locate Open Ports in Linux

Reading Time: 9 minutes

What is a Port? 

First, let’s define what a port is. According to the IEFT, a port is: 

A logical entity for Internet communication. Ports serve two main purposes:
1. They provide a demultiplexing identifier to separate transport sessions between the same pair of endpoints
2. They may also identify the application protocol and associated service to which processes connect.

In plain English, this simply means that a port is an endpoint through which data flows back and forth between two computers over a network. A computer has 65535 ports available to share information. These port numbers are based on a 16-bit number, which is where we derive the total number of available ports (0 to 65535).

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How to Use Telnet To Check SMTP Service

Reading Time: 3 minutes

One of the most common email issues we encounter is customers who are traveling and encounter problems trying to send an email. This is often the result of connecting to a new network that hasn’t been used to send email before, as an open wireless network in a coffee shop, library, or other public location. Every network has rules, and in some cases, networks have rules about what outbound email servers (SMTP) you can connect to and use.

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