What is Port 631?
by Erik Mikac | Published on March 07, 2025
Port 631 is dedicated to the Internet Printing Protocol (IPP), which is an HTTP-based protocol that allows you to securely print documents over a TCP/IP network.
To understand the purpose of port 631, you need to understand IPP.
IPP is a client-server protocol that lets a device send a print job to a network printer for printing. It does this using common HTTP commands. The protocol is incorporated into modern operating systems such as Windows and Linux, and it supports authentication and access control as well as encryption.
When using the IPP protocol, you do so over port 631.
Port 631 is one of the many TCP ports that network administrators must understand and support.
How Port 631 Works
Port 631 supports IPP. It lets devices send print jobs to a network printer using common HTTP commands.
Definition and Primary Purpose
The primary purpose of port 631 is to support IPP. It allows users to print documents over a network efficiently and securely.
Connection Protocols Involved
When using IPP over port 631, you use other protocols as well. You use HTTP to send documents to the printer and to receive their status, through POST and GET commands, respectively. Beneath this, you use the Transport Control Protocol (TCP) as a transport protocol. You use TCP instead of User Datagram Protocol (UDP) because it supports the reliable and authenticated connections necessary for printing to network printers.
Common Devices and Systems Using Port 631
All modern operating systems support IPP over port 631. Windows supports it through the Internet Printing Client. Linux and other Unix-like operating systems, such as MacOS, support it through CUPS (Common Unix Printing System).
Most modern printers support IPP over port 631.
Port 631 in Network Security
There are security issues when using IPP over port 631. You need to be aware of them and how you can mitigate them.
Potential Vulnerabilities
While using IPP over port 631 is more secure than other printing protocols, it is not immune from serious vulnerabilities. These include remote code executions (RCEs). The protocol can also be susceptible to various exploits if you don’t set it up properly.
Security Measures and Best Practices
You should limit access to port 631 on your network printers to trusted networks. You should also implement encryption, set up proper access control, and monitor traffic over the port. Finally, you should always keep your system software up to date.
Troubleshooting Common Issues
The most common issues you may face when running IPP over port 631 relate to configuration and connectivity. You need to make sure that you’ve configured your printers properly and that they allow connections from other devices through your firewalls.
Port 631 and Printing Protocols
Port 631 and IPP support network printing. You can use them to send documents to a printer and to receive the status of print jobs.
Overview of Internet Printing Protocol (IPP)
IPP lets devices print documents to network printers over port 631. When a user wants to print a document, they use IPP over the port to send the document to the printer. They can do this even if they’re working remotely.
How Port 631 Facilitates Printing Services
Port 631 facilitates printing services by allowing clients to communicate with printers. They can send documents over the port for printing, and they can request the status of their print jobs over the port.
Port 631 Alternatives and Comparisons
The alternative to using IPP over port 631 is using raw printing over port 9100. Both support printing documents over a network, but each has its strengths and weaknesses.
Other Ports Related to Printing and Data Transfer
An alternative to using IPP over port 631 is the use of raw printing over port 9100. They both allow you to print documents to a network printer.
When to Consider Using Other Ports
If print speed is your prime concern, or you need to support legacy printers, using raw printing over port 9100 may be a better choice than using IPP over port 631. However, IPP is far more secure than raw printing and has better features and better support for modern printers.
FAQs About Port 631
The following FAQs answer questions typically asked relating to port 631. They provide a basic understanding of the port and its uses.
What Devices Typically Use Port 631?
Two types of devices typically use port 631. Client devices, such as computers and tablets, use the port to send print jobs, and printers use the port to receive these jobs.
How Can I Secure Port 631 on My Network?
You can secure port 631 on your network by limiting access to the port on your network printers to trusted networks. You should also implement encryption, set up proper access control, monitor traffic over the port, and always keep your system software up to date.
What are the Risks of Leaving Port 631 Open?
Leaving port 631 open on your network printers can lead to a number of serious vulnerabilities, including RCEs. To mitigate them, you should follow the guidelines described in the Security Measures and Best Practices section.
Can Port 631 Affect My Printer’s Performance?
Using IPP over port 631 shouldn’t dramatically affect your printer’s performance. However, if speed is a pressing concern, you can consider using raw printing over port 9100 as an alternative. Keep in mind that raw printing isn’t as secure as IPP, nor does it have the features of IPP.
Is Port 631 Necessary for Home Networks?
If you have a printer that you want devices on your home network to reach, then you need port 631 open on the printer. Alternatively, you could close the port and use raw printing over port 9100, but this solution has serious drawbacks.
Conclusion
Port 631 is used for IPP. It lets clients on a network send print jobs to a network printer using HTTP commands. While the protocol is far more secure than using raw printing over port 9100, you still need to know how to protect the port from serious vulnerabilities.