Linux firewall and network printer HP LaserJet
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Today I was presented a small problem: after you add a network printer HP Color LaserJet 2840 to a LAN I configured the client because print to that printer using the protocol CUPS printing. On the client runs Debian GNU / Linux firewall-protected iptable. Although the printer was identified, was unable to start printing a document without first disable the firewall.
Analysis and resolution of the problem required only a few minutes! After a begun on `` tail / var / log / messages I launched a test print:
#tail -f /var/log/messages I immediately obtained a video log these lines generated by iptable:
Mar 18 12:34:53 localhost kernel: DROPPED IN= OUT=eth2 src=192.168.1.112 DST=192.168.1.138 LEN=78 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=1700 DPT=161 LEN=58
Mar 18 12:34:53 localhost Officejet_6300_series?ip=192.168.1.138: INFO: open device failed; will retry in 30 seconds...
In other words, the exchange of packets on UDP port 161 was blocked (in nerdese: dropped) from the firewall. It is enough to add a firewall rule to allow for the transit of UDP packets on that door to solve the problem.
