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I have two printers connected on a local lan through a cable modem and both spontaneously changed their IP addresses. For example, one was 10.1.10.236 and by looking at the LCD screen on the printer I could see that it had changed to 10.1.10.237

This caused a problem because my CUPs printer definition file has the URI to the printer hard coded as 10.1.10.236 so basically the printer stopped working until I edited and changed the printer URI. I am using Arch Linux, so I used lpadmin to do this.

Should I be concerned that the printer local address just changed all by itself? Is this a security problem?

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    So I take it you’re relying on DHCP to assign addresses in your network, correct?
    – Daniel B
    Commented Aug 5, 2020 at 20:24
  • This is common with printers that connected by a DHCP address. Change the printers to Static IP and the problem should go away.
    – anon
    Commented Aug 5, 2020 at 20:25
  • @DanielB How would I determine that? The Arch Linux just said to read the IP address off the LCD screen of the printer and enter that into the URI for the printer. It did not say anything to indicate HOW the printer determines its own IP address.
    – Tyler Durden
    Commented Aug 5, 2020 at 21:23
  • If you want to avoid being dependent on the actual address I suggest checking the hostname of the printer and using that one insteat. For this you would also need to setup mdns on your arch linux computer.
    – jvda
    Commented Aug 5, 2020 at 21:56
  • If you want us to advise you how to give the printer a fixed address, please tell us the model name(s) of the printers.
    – hdhondt
    Commented Aug 5, 2020 at 23:11

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Should I be concerned that the printer local address just changed all by itself?

Yes, it is an indication of poor systems administration.

Is this a security problem?

Potentially. If the administrative error is pervasive, if there can be other printers at out of sight locations and sensitive data is printed.

P.S. don't take the above as personal criticism. The farcical situation you describe arises largely because of broader societal values and the inevitable effect they have on developers of mass market operating systems in an era when printers cost less than a weeks supply of ink and computers cost less than lunch. The demands of convenience, instant gratification, security and backwards compatibility are sometimes irresolvable

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If you have not set a fixed IP address on the printer itself or created a DHCP reservation for the printer’s MAC address on the cable modem (which is actually a router), the printer’s IP address can simply change whenever. Some DHCP servers make an effort to keep addresses stable, but there’s no guarantee.

I suggest you first try to set up a DHCP reservation on the cable modem. You may be able to do so from the list of connected devices.

If you cannot or don’t want to setup a DHCP reservation, you can also set a static address on the printer. It has to be in the same subnet, but preferably outside the DHCP range. So maybe something like 10.1.10.2 with subnet mask 255.255.255.0. Check your router’s DHCP settings for the DHCP range.

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