issues with printing

Hi, hope someone can help…

I am printing through gateway. My computer is part of univeristy network. Since I have installed Comodo Personal Firewall printing really slowed down. I mean really slowed down. I have to wait for couple of minutes for file to be sent to printer.

Any clues what might be wrong (or is this normall behavior)?


You may need to add a rule for your print server so that CPF will allow necessary traffic. Adding the local area network as a trusted zone would do the same, if you want to trust the network.


Many thanks Egemen,

I do not want to trust the network. It is university network with many machines connected. If someone breaks in one of these then it could break into mine I fear.

Which special rule for printer server do you have in mind? I am already allowing all outgoing connections (list of network rules attached). I can connect to printer and print. What special rule should I use to make connection faster?

Quote: “I am going to understand how CPF works even if I have to die” (seen it on the forum) :).


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I addedd network rule that said

Allow & Log, TCP in, Source=printer_gateway, Remote=my machine, source port=any, remote port=445

and put it above (so it is processed first before) default rule that blocks everything (please see attachment).

Now, why this worked? First, why it did not work before?

Funny, when I wanted to print, I realized that my computer sent “ECHO REQUEST” to printer server, not SYN (first step of three handshake procedure). Here comes real surprize. Printer server replied with SYN instead (starting three handshake procedure), probably due to ECHO REQUEST sent by my computer. Why is this so I have no clue.

My old rules blocked this SYN as unsolicitated inbound request. Printer server continied bombarding my computer with these, but these were constantly refused.

Now, with new rule I added, SYN (a reply for ECHO request) from Printer server gets accepted and everything works perfectly.

This is definitively one sample for examples library. :wink:

Now, two questions can be immediatelly asked.

(1) The problem is, did I open myself too much for attack and which type of attack? Could someone pretend to be Printer server and get in through the rule I just inserted? Okay, this one is probably for security gurus on the forum …

(2) How come I could print with old settings? Did my computer got boread to death and decided to send the stuff (for printing) anyway to printer server?


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