Firewall ports

Default open ports:-

open TCP ports : 20,21,22,25,53,80,110,143,443,587,666,993,995,3306,8080,8081,10000
open udp ports:

Email Protocols - POP3, SMTP and IMAP

What is POP3, IMAP, SMTP and which are the default ports for them

In this tutorial we will provide you with detailed information about the most commonly used Email protocols on the internet - POP3, IMAP and SMTP. Each one of them has specific function and way of work. Read on to see which configuration will best server your particular email needs.

This tutorial covers the following topics:What is POP3 and which are the default POP3 portsWhat is IMAP and which are the default IMAP portsWhat is SMTP and which are the default SMTP ports

What is POP3 and which are the default POP3 ports

Post Office Protocol version 3 (POP3) is a standard mail protocol used to receive emails from a remote server to a local email client. POP3 allows you to download email messages on your local computer and read them even when you are offline. Note, that when you use POP3 to connect to your email account, messages are downloaded locally and removed from the servers. This means that if you access your account from multiple locations, that may not be the best option for you. On the other hand, if you use POP3, your messages are stored on your local computer, which reduces the space your email account uses on your web server.

By default, the POP3 protocol works on two ports:

  • Port 110 - this is the default POP3 non-encrypted port
  • Port 995 - this is the port you need to use if you want to connect using POP3 securely

What is IMAP and which are the default IMAP ports

The Internet Message Access Protocol (IMAP) is a mail protocol used for accessing email on a remote web server from a local client. IMAP and POP3 are the two most commonly used Internet mail protocols for retrieving emails. Both protocols are supported by all modern email clients and web servers.

While the POP3 protocol assumes that your email is being accessed only from one application, IMAP allows simultaneous access by multiple clients. This is why IMAP is more suitable for you if you're going to access your email from different locations or if your messages are managed by multiple users.

By default, the IMAP protocol works on two ports:

  • Port 143 - this is the default IMAP non-encrypted port
  • Port 993 - this is the port you need to use if you want to connect using IMAP securely

What is SMTP and which are the default SMTP ports

Simple Mail Transfer Protocol (SMTP) is the standard protocol for sending emails across the Internet.

By default, the SMTP protocol works on three ports:

  • Port 25 - this is the default SMTP non-encrypted port
  • Port 2525 - this port is opened on all SiteGround servers in case port 25 is filtered (by your ISP for example) and you want to send non-encrypted emails with SMTP
  • Port 465 - this is the port used, if you want to send messages using SMTP securely

Well known ports

20 – FTP Data (For transferring FTP data)

21 – FTP Control (For starting FTP connection)

22 – SSH (For secure remote administration which uses SSL to encrypt the transmission)

23 – Telnet (For insecure remote administration)

25 – SMTP (Mail Transfer Agent for e-mail server such as SEND mail)

53 – DNS (Special service which uses both TCP and UDP)

67 – Bootp

68 – DHCP

69 – TFTP (Trivial file transfer protocol uses udp protocol for connection less transmission of data)

80 – HTTP/WWW(Apache)

88 – Kerberos

110 – POP3 (Mail delivery Agent)

123 – NTP (Network time protocol used for time syncing uses UDP protocol)

137 – NetBIOS (nmbd)

139 – SMB-Samba (smbd)

143 – IMAP

161 – SNMP (For network monitoring)

389 – LDAP (For centralized administration)

443 – HTTPS (HTTP+SSL for secure web access)

514 – Syslogd (udp port)

636 – ldaps (both ctp and udp)

873 – rsync

989 – FTPS-data

990 – FTPS

993 – IMAPS

1194 – openVPN

1812 – RADIUS

995 – POP3s

2049 – NFS (nfsd, rpc.nfsd, rpc, portmap)

2401 – CVS server

3306 – MySql

3690 – SVN


Note 1: If protocol(TCP or UDP) is not mention then the above port are solely for TCP. Some service use UDP as mention in above list.

Note 2: X11 use 6000 to 6063.. ports for connecting X11 from remote server.

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