printer problem

[vu pham]

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