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FriedrichNietzsche

Member

Registered: 2018-09-05

Posts: 46

[Solved] How to use a scanner sitting in a different subnet

Hi,

I recently split my home network into different subnets and my canon mx925 printer was moved to one of those. While I was still able to print by changing the URL for the printer in the settings, I still havent figured out how to do the same with scanning. simple-scan is unable to find the printer and I have not found any way to point it directly to it. Can someone tell me how to do that? Thanks!

Last edited by FriedrichNietzsche (2024-07-25 10:36:36)

cryptearth

Member

Registered: 2024-02-03

Posts: 606

Re: [Solved] How to use a scanner sitting in a different subnet

first question: why you changed your network configuration?
then: you need a router between two different subnets for them to be able to communicate and set up the required routing tables
also: I guess it's a consumer grade device just not designed to be accessed across routers from a different subnet but s meant to work within the same local subnet - so basically: RTFM and You're doing it wrong!

Last edited by cryptearth (2024-07-24 16:19:48)

FriedrichNietzsche

Member

Registered: 2018-09-05

Posts: 46

Re: [Solved] How to use a scanner sitting in a different subnet

first question: why you changed your network configuration?

Why is it your concern? But since you asked: I host about a dozen externally reachable services and I don't want someone after a potential breach to waltz through my network.

then: you need a router between two different subnets for them to be able to communicate and set up the required routing tables

Well - since like I have stated - printing is working, I guess I must have set up routing properly on my Openwrt router. The printer sits in a different vlan in a different network than my desktop.

also: I guess it's a consumer grade device just not designed to be accessed across routers from a different subnet but s meant to work within the same local subnet

This is a software/config problem on my desktop. The scanner works. If I can contact a network client, it can reply to me. Thats how networks work. Gnomes simple-scan software cannot find it though, I guess because the scan is only limited to the local network range.

so basically: RTFM and You're doing it wrong!

I have the feeling that your whole point for your reply was to post this phrase while barely knowing whats going on. And well you also failed to properly read my request.

cryptearth

Member

Registered: 2024-02-03

Posts: 606

Re: [Solved] How to use a scanner sitting in a different subnet

contradicting to you observation of the reason for my reply I do understand why you've changed your network ... now that you explained it (off-topic: that's the problem with you paranoid folks: you think the sorld is all evil and you have to wall yourself off like this "none of your business" - but then still ask for help for some self introduced issue expecting everyone else to have magic powers to know your specific setup which often turns out to be the problem noone is aware of cause you had god knows whatever reason to not tell us - HOW do you expect us to help?)
although I honestly don't really see the reason as to why someone would even try to do this you already found the issue: the tools you want to use are not designed for such a setup of yours cause thier devs never expected someone to do such weird stuff
can it work - sure - but don't expect off-the-shelf-tools to work with whatever you came up with for whatever reason out of the box ... and don't blame them cause they're not designed for that

to me the solution will likely involve one of two scenarios:

a) going the easy route and just migrate your device to the same subnet where the tools you want to use expect it to be - or just use usb which this device likely has
b) going down the rabbit hole deeply and end up with lots of tinkered-with crap just to discover the firmware of your device just can't handle it

just because a printer/scanner multi-function-device has a rudimentary network stack and you may can reach it from your desktop doesn't imply its likely limited feature set is able to do the same in reverse
this question is better placed at the manufacturer support lije "uhm, does your devife X support my use case?"

just because something maybe can be done doesn't mean it should be against all odds

btw: I host some public accessible service here at home myself - and yes - it did got hacked because I was too lazy to apply a fix for log4j
so I experienced what you try to defend against first hand - don't try to teach me just because I deal with it going the easy way

seth

Member

Registered: 2012-09-03

Posts: 56,103

Re: [Solved] How to use a scanner sitting in a different subnet

How do you access the scanner in the first place?
Eg. sharing it via sane include a netmask, and all default config examples tell you how to open it to the /24 subnet…
For bjnp and mfnp you'd need ~8610-8613 bridged, if there's a firewall typically also allow UDP here.

Have you tried to nmap the pranner (scrinter?) in both subnets and see which ports are available/open in either context?

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FriedrichNietzsche

Member

Registered: 2018-09-05

Posts: 46

Re: [Solved] How to use a scanner sitting in a different subnet

Ok, in the meantime I've figured it out.

I needed to install the package sane-airscan and then add my pranner/scrinter (lol, I like that one!) to the config in /etc/sane.d/airscan.conf. The way how to do it is described can be found here. In order to get the specific url/endpoint for the device it is advisable to connect the printer again in the same local network as your PC and run airscan-discover in terminal. This will print out every found scanner in the same network as the scanning machine. Then you can use the (adapted) network address for your pranner/scrinter in the airscan config and move it back into the proper network. After that simple-scan is able to find the scanner.

@cryptearth: Geeez, maybe just don't reply if you cannot contribute something of value? Especially if your comment basically only has the single purpose of throwing in a RTFM? Next time if you see a topic opened by me please just ignore it.