Lexmark 7500 Series Printer - GPL?

I am yet another frustrated Linux user, frustrated at lack of support from peripheral suppliers (such as Lexmark, when it comes to the 7500 Series Printer).

Note that the X7500 appears to be an office printer, and the X7550 appears to be a home printer. Lexmark are inconsistent in their naming, for example, I don't believe that the X7500 firmware update mentioned on their webpage can be applied to the X7550 printer (which Lexmark says is in the X7500 series).

A quick look at the printer, however, suggests that it may not be as incompatible as you may first think ...

When scanning / printing, the port 9100 is used. Using Wireshark, it is clear that the sequence 'HBN3' is passed over this interface.

Reading a Lexmark White Paper on multi-function printers, it can be seen that there is, indeed, an 'HBN3' protocol, a quick check shows that there are other standard ports available and open too:

Default Print (TCP 9100)
HBN3 (TCP 9100)
FTP - File Transfer Protocol (TCP 21)
HTTP - Embedded Web Server (EWS) (TCP 80, 8000)
mDNS (Bonjour) - Auto Configuration and Discovery (UDP 5353)
SNMP V2c/V1 - Simple Network Messaging Protocol (UDP 161)
SNMP V1 Traps (UDP 162)
HBN3 HID - Human Interface Device (UDP 162)
HBN3 Scan (TCP 9100)
IPP (TCP 631) - Timed Out!
Telnet (TCP 10000) - Command Line Facility

Now, port 10000 looks extremely interesting. When you connect, you get the LXK: prompt, and the prompt has built-in help.

Connected to 192.168.2.22 (192.168.2.22).
Escape character is '^]'.
LXK: enable
LXK: ls
LXK: netstat -a

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:8000 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:9100 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:10000 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:21 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:631 0.0.0.0:* LISTEN
tcp 0 0 192.168.2.22:10000 192.168.2.11:59064 ESTABLISHED
udp 0 0 0.0.0.0:9100 0.0.0.0:*
udp 0 0 0.0.0.0:161 0.0.0.0:*
udp 0 0 0.0.0.0:5353 0.0.0.0:*

LXK: ps

PID Uid VmSize Stat Command
1 root 512 S init
2 root SWN [ksoftirqd/0]
3 root SW [events/0]
4 root SW [khelper]
5 root SW [kthread]
8 root SW [kblockd/0]
11 root SW [khubd]
34 root SW [pdflush]
........

Now this looks like an embedded Linux release - I wonder where the GPL sources can be downloaded?

Update: Well, on the 30th April 2009, Lexmark uploaded their GPL code to ftp://ftp.lexmark.com/swlab/. It would be great if this happened before, and I'd have found a note in the user manual telling me where the sources could be found! But it's good to see that Lexmark have done the right thing in the end!

"Corresponding Source conveyed, and Installation Information provided, in accord with this section must be in a format that is publicly documented" - GPLv2.

I've recently bought the HP J4680 for £90, which works over a wireless network for printing, scanning and faxing, all with Linux.

References

1. Lexmark 7500 Series User Manual
   
2. IP Ports Utilized by 2007 and 2008 Inkjet Products ID: ENUS26689
3. Lexmark Security White Paper
4. Open Printing Database
5. HP J4680 Printer