[Discuss] CUPS Remote Printer

[John Blomfield]

Murray Strome wrote:
> My main printer is an Okidata OL600e B&W LED printer which is 
> physically connected to my wife's printer.  Through new installs, 
> upgrades, etc. I have never really had to do much to have it 
> accessible to all my computers.  However, since re-installing Kubuntu 
> on my wife's computer, I cannot no longer access it.  I imagine that 
> it has something to do with my ability to access her computer. I have 
> not changed any settings in my routers. The simplified configuration is:
>
>
>    --------                   ---------------          -----------------
>   | router|------------------|  Computer 1  |----------|Okidata Printer|
>   |       |----               ---------------          -----------------
>   --------     |
>                |                 --------------      ---------------
>           |  router #2 |------|  Computer 2 |
>           --------------      ---------------
>                            
> Of course, there are other computers connected to router & router 2, 
> and other printers on both Computer 1 and Computer 2. The first router 
> is connected to a cable modem box, then to Shaw cable.
>
> All the computers used DHCP to get their addresses, as do the 
> routers.  I have changed Computer 1 to fixed address (one the router 
> originally assigned to it), but that did not make any difference.
>
> From Computer 2, I can ping router or Computer 1 (or anything else 
> connected on that router) from Computer 2. I can ping router 2 from 
> Computer 1 using the address "leased" to it by router, but I cannot 
> ping to Computer 2 from Computer 1.  I can connect to the internet 
> from everywhere without any problem.  If I try to add a network CUPS 
> printer in Computer 2, it cannot access Port 631 on the address 
> assigned to Computer 1 by router.
>
You need to open the router #2 firewall so that computer 1 can see 
computer 2.  It depends on the brand of router and its software how you 
do this.  Have a look and the firewall rules for router #2, it should 
have a menu item that allows you to do this.  As a last resort you could 
put Computer 2 in the DMZ (Demilitarized Zone) as it would still be 
protected by the other router.  Incidentally why do you need router #2 
would not a switch do just as well unless it has to be secure from 
Computer 1 and the others on router?

John Blomfield

> As mentioned, I really did not have to do anything after previous 
> reinstallations to have access to all the printers on all the 
> computers from every computer.  I don't know what has changed. I seem 
> to remember some security advice a while ago which recommended that 
> UPNP should be disabled, which I did on both routers, but CUPS was 
> still working OK long after I did that.
>
> Any suggestions?
>
> Thanks.
>
> Murray
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