Port forwarding allows remote access to devices on a private network by enabling communication endpoints identified by port numbers. To enhance security, it's recommended to forward ports only to devices in a DMZ, limit access to specific ports and IP addresses, or avoid port forwarding altogether using alternatives like secure VPN tunnels. The document also outlines common port usages, including those for FTP, SSH, and HTTP.

1. PORT FORWARDING
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2. WHAT IS PORT FORWARDING?
• Port forwarding, also known as port management, allows remote servers and devices on
the internet to be able to access devices that are on a private network.
• If you are not using port forwarding, only devices on that private internal network can
have access to each other or your network.
• A port is a communication endpoint and is identified as a port number that is always
associated with an IP address.

3. Four ways to mitigate the security impact of port forwarding
• 1. Only forward ports to devices in a DMZ
• 2. Only forward the specific ports that are required
• 3. Restrict the IP addresses that are allowed to access the port forward.
• 4. Don't port forward at all.

4. ONLY FORWARD PORTS TO DEVICES IN A DMZ
• Forwarding ports through a DMZ gives you an extra layer of security and protects
your network from being vulnerable.
• A DMZ or demilitarized zone is a perimeter that protects and adds an extra layer of
security to an organization’s internal network from untrusted outside traffic.

6. ONLY FORWARD THE SPECIFIC PORTS THAT ARE
REQUIRED
• Forwarding to specific ports that you need will make your network much safer.
• If you were to forward to lots of different ports that may not be necessary, you could be
opening up your network to cyber-attacks and data breaches.

7. RESTRICT THE IP ADDRESSES THAT ARE
ALLOWED TO ACCESS THE PORT FORWARD.
• If you aren’t restricting IP addresses, your server could be accessed by a malicious
source.
• You can allow access to specific IP addresses so that only those IP addresses have
access to your server.
• If you have a vendor that requires access to a server that you manage, then you can
restrict access to the port forward for that server to only the IP addresses that your vendor
uses.

8. DON'T PORT FORWARD AT ALL.
• Instead of port forwarding, you can use services like SASE which uses secure VPN
tunnels to allow authenticated and secured access to resources.

9. Local Port Forwarding
Local Port Forwarding is the common type of port forwarding. It is used to let a user
connect from the local computer to another server, i.e forward data securely from another
client application running on the same computer as a Secure shell client. By using local port
forwarding , firewalls that block certain web pages are able to Bypass.
Remote Port Forwarding
This form of port forwarding enables applications on the server side of a secure shell.
There are proprietary for the same general purpose. To use remote port forwarding the
address of the destination server and two port number must be known. The port number
chosen depend on which application is to be used.

10. Port Number Usage
20 File Transfer Protocol (FTP) Data Transfer
21 File Transfer Protocol (FTP) Command Control
22 Secure Shell (SSH)
23 Telnet - Remote login service, unencrypted text messages
25 Simple Mail Transfer Protocol (SMTP) E-mail Routing
53 Domain Name System (DNS) service
80 Hypertext Transfer Protocol (HTTP) used in World Wide Web
110 Post Office Protocol (POP3) used by e-mail clients to retrieve e-mail from a server
119 Network News Transfer Protocol (NNTP)
123 Network Time Protocol (NTP)
143 Internet Message Access Protocol (IMAP) Management of Digital Mail
161 Simple Network Management Protocol (SNMP)
194 Internet Relay Chat (IRC)
443 HTTP Secure (HTTPS) HTTP over TLS/SSL
14 common network ports