printer problem

[C M Reinehr]

Vu,

On Thu 04 December 2008 09:54, vu pham wrote:
> Andrew Gould wrote:
> > On Wed, Dec 3, 2008 at 2:37 PM, Vu Pham <vu at sivell.com
> > <mailto:vu at sivell.com>> wrote:
> >
> >
> >     I have a network printer using LPD. When I *manually* telnet to that
> >     printer at LPD port, then the printer does ACK to my SYN packet and
> >     start receiving data.
> >
> >     When I use CUPS to print, then the printer does not acknowledge the
> >     tcp SYN packets at all.
> >
> >     They are just TCP connections, how does the printer know ? :(
> >     Below is my tcpdump:
> >     All packets before 14:24:54 are from my manual telnet.
> >     All packets after 14:25:06 are from CUPS.
> >     Pluto is my server, 192.168.1.110 <http://192.168.1.110> is the
> > printer
> >
> >     As you can see, CUPS attempted to send SYN packets but does not get
> >     ACKED.
> >
> >     I can only see the difference of the source ports, but does the
> >     printer care about that ?
> >
> >     -------------- start of tcpdump -------
> >     [root at jetco ~]# tcpdump host 192.168.1.110 <http://192.168.1.110>
> >     tcpdump: verbose output suppressed, use -v or -vv for full protocol
> >     decode
> >     listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
> >     14:24:50.555796 IP pluto.51602 > 192.168.1.110.printer: S
> >     3462708113:3462708113(0) win 5840 <mss 1460,nop,nop,sackOK,nop,wscale
> > 2> 14:24:50.764192 IP 192.168.1.110.printer > pluto.51602: S
> >     3520144456:3520144456(0) ack 3462708114 win 4096 <mss 1452,nop,wscale
> > 0> 14:24:50.764207 IP pluto.51602 > 192.168.1.110.printer: . ack 1 win
> > 1460 14:24:54.396898 IP pluto.51602 > 192.168.1.110.printer: F 1:1(0) ack
> > 1 win 1460
> >     14:24:54.409157 IP 192.168.1.110.printer > pluto.51602: . ack 2 win
> > 4380 14:24:54.409700 IP 192.168.1.110.printer > pluto.51602: F 1:1(0) ack
> > 2 win 4380
> >     14:24:54.409714 IP pluto.51602 > 192.168.1.110.printer: . ack 2 win
> > 1460
> >
> >
> >
> >     14:25:06.560950 IP pluto.731 > 192.168.1.110.printer: S
> >     3473251429:3473251429(0) win 5840 <mss 1460,nop,nop,sackOK,nop,wscale
> > 2> 14:25:09.560695 IP pluto.731 > 192.168.1.110.printer: S
> >     3473251429:3473251429(0) win 5840 <mss 1460,nop,nop,sackOK,nop,wscale
> > 2> 14:25:15.560267 IP pluto.731 > 192.168.1.110.printer: S
> >     3473251429:3473251429(0) win 5840 <mss 1460,nop,nop,sackOK,nop,wscale
> > 2> -------------- end of tcpdump -------
> >
> >     Any advice, please  ?
> >
> >     Thanks,
> >
> >     Vu
> >     _______________________________________________
> >
> >
> > Doesn't CUPS use IPP port by default?  Could this be the problem?
>
> Thanks, Andrew. I think it is the firmware of the printer having some
> bugs or maybe it has some special settings that I don't know. I posted
> an email this morning how I solved it :)
> This is a big multi-function printer leased from some office-supply
> company. They set some password so I cannot look into the settings.
> Calling them takes more time than that for me to fix it :)
>
> Vu

In my experience, most such problems are a matter of correctly configuring the 
CUPS system for the type of printer being used. Check out the 
subsection, "Common Network Printer URIs" on this page, "Using Network 
Printers": http://www.cups.org/documentation.php/network.html

HTH

cmr

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