Analysis and Review

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What firewall ports open for a printer?

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So you need to open up some ports in your firewall for your network printer.

Well almost all network printers use the same ports. So far from what I’ve seen they all use:

  • port 515, prints to destination port 515 in LPR mode
  • port 721-731, LPR (RFC 1179 Compliant)
  • port 9100, source ports from ephemeral ports (9100 default)

So if you need to open some holes in your firewall for printing purposes remember the destination ports to open are 515 and 9100. If that doesn’t get it also open 721 through 731.

Obtain the Port Information From the Local Machine

Alternatively, if you have access to the computer that is trying to print you can you can see what port was specified during installation by following these steps.

  1. Start -> Printers and Faxes, or Start -> Control Panel -> Printers and Faxes.
  2. Right-click the printer name and then choose “properties”.
  3. Click the tab labeled “ports” and the port number(s) will be listed at the end of the IP address.

Capture the Port Information over the Network

  1. Capture the port number with a packet capture from your Cisco switch.
  2. Capture the port number with a packet capture from your Cisco ASA firewall.
  3. Capture the port number with a packet capture using TCP Dump and Wireshark.

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