Rob Vinson

Lantronix Serial-to-ethernet

Serial-to-Ethernet Devices

I’ve come across various serial-to-ethernet adapters over the years. What’s a serial-to-ethernet adapter? They allow you to plug in some device that communicates information via serial (E.G. RS-232) into an IP network. For example, maybe you have some temperature sensor shares out readings via a serial interface. You hook this sensor into an IP network via a serial-to-ethernet adapter. VoilĂ , now you can get your readings from your desktop, server, etc.


Recently I’ve crossed paths with some Lantronix serial-to-ethernet adapters.

Some notable things that stand out on these devices:

  • Web-based configuration has a blank default username/password
  • Telneting to 9999/TCP offers up another means of configuration, again no password is necessary by default.
  • 30718/UDP runs a service by which information about the device can be queried, and configuration may be done.


There are many functions available over 30718/UDP. After some some time googling, I discovered a zip file containing documents which detail these functions.

  • Node reset (03)
  • Firmware version query (F6)
  • Response to firmware version query (F7)
  • Setup record query (F8)
  • Response to setup record query (F9)
  • Set configuration – supplying a setup record (FA)
  • Response to set configuration (FB)
  • Set IP address (FC)

So, the device can be reset, configured, and have its IP address changed all via UDP, huh…

Particularly funny is that response to a setup record query has a field for “telnet config password”. If I’m understanding correctly, if 9999/TCP has a password, you can just look up the password over 30718/UDP.

Scanning for Lantronix Devices

My Metasploit scanner module can be found at robvinson/metasploit-modules on GitHub.

What a scan looks like:

msf > use auxiliary/scanner/scada/lantronix_discover
msf  auxiliary(lantronix_discover) > set RHOSTS
msf  auxiliary(lantronix_discover) > run

[+] Found - Lantronix Device type: UDS-10/Cobox 4.X
[+] Found - Lantronix Device type: XPort-03/04
[*] Scanned 256 of 256 hosts (100% complete)
[*] Auxiliary module execution completed

Update – 01/30/2013

Looks like some others stumbled across lantronix and there are metasploit modules! One extracts the telnet password, and one grabs the version from a telnet banner.