[INFO] Network printer not detected

[INFO] Network printer not detected

Postby mla » Jul 5th, '15, 11:58

Here's a very odd wrinkle which may be causing a few people some grief. I have an HP printer which has no interfacse other than wifi. It does not get automatically detected either by system-config-printer (which is what MCC->Hardware->Printing uses) nor by hp-setup (the hplip printer setup utility), despite the fact that there is no firewall on the machine. Not a big problem, since I happen to know the printer's IP address, which does the trick, but puzzling none the less.

I have now discovered, entirely by accident that both utilities do detect the printer if (a) the firewall is enabled and (b) the ethernet interface is checked off. I.e. the firewall is defined but not applied. Very odd. Probably affects all network printers and/or scanners, not just HP ones.
mla
 
Posts: 255
Joined: Sep 16th, '11, 16:10

Re: [INFO] Network printer not detected

Postby doktor5000 » Jul 6th, '15, 10:50

Or it might be that the nmap parsing is broken again :/
Maybe something similar to this one crept in again: https://bugs.mageia.org/show_bug.cgi?id=12781
Cauldron is not for the faint of heart!
Caution: Hot, bubbling magic inside. May explode or cook your kittens!
----
Disclaimer: Beware of allergic reactions in answer to unconstructive complaint-type posts
User avatar
doktor5000
 
Posts: 14608
Joined: Jun 4th, '11, 10:10
Location: Leipzig, Germany

Re: [INFO] Network printer not detected

Postby mla » Jul 6th, '15, 16:25

Not clear how nmap is to blame, since it *does* work under the conditions I described. As usual, though, there is yet more to it, as a bit more poking about shows.

For auto-dicsovery to work, "network services autodiscovery" must be enabled in the firewall. This may not seem surprising, until I add that this is the case whether or not the firewall is disabled! To put it otherwise, if you do not wish firewall enabled, you must still enable autodiscovery in the firewall before disabling the firewall.

Auto-discovery will also work if the firewall is enabled, but not applied to Ethernet interface(s). This is true even if having enabled the firewall (without services autodiscovery) you are still looking at the window asking you which interface(s) it should be applied to. Until you click OK to confirm applicability to your Ethernet interface(s), auto-discovery will work. Once you click OK, with Ethernet interface(s) checked, it will stop working.

Doesn't sound like an nmap problem to me. :-)
mla
 
Posts: 255
Joined: Sep 16th, '11, 16:10

Re: [INFO] Network printer not detected

Postby doktor5000 » Jul 6th, '15, 20:19

mla wrote:For auto-dicsovery to work, "network services autodiscovery" must be enabled in the firewall. This may not seem surprising, until I add that this is the case whether or not the firewall is disabled! To put it otherwise, if you do not wish firewall enabled, you must still enable autodiscovery in the firewall before disabling the firewall.

Auto-discovery will also work if the firewall is enabled, but not applied to Ethernet interface(s). This is true even if having enabled the firewall (without services autodiscovery) you are still looking at the window asking you which interface(s) it should be applied to. Until you click OK to confirm applicability to your Ethernet interface(s), auto-discovery will work. Once you click OK, with Ethernet interface(s) checked, it will stop working.


I think that should be reported as a bug against our firewall configuraton.
Cauldron is not for the faint of heart!
Caution: Hot, bubbling magic inside. May explode or cook your kittens!
----
Disclaimer: Beware of allergic reactions in answer to unconstructive complaint-type posts
User avatar
doktor5000
 
Posts: 14608
Joined: Jun 4th, '11, 10:10
Location: Leipzig, Germany

Re: [INFO] Network printer not detected

Postby mla » Jul 6th, '15, 22:08

mla
 
Posts: 255
Joined: Sep 16th, '11, 16:10


Return to Printers and Scanners

Who is online

Users browsing this forum: Bing [Bot] and 1 guest