BillFitzmaurice.info

I'm trying to fix a problem with a piece of equipment (a bug in the firmware of a PTZ camera). I need a small utility that can monitor traffic on an outgoing UDP port, wait for a specific string, monitor return data on the incoming UDP port, and alter the response string by stripping out four hex pairs that are extraneous before the return data gets to the control program.

I can provide more specific info, just trying to outline the basic skill set needed here.

Any takers? PM Me. Thanks!

Brent, that is so far above my head that I feel like Charlie Brown......

Bruce Weldy wrote: ↑Thu Sep 24, 2020 10:13 am Brent, that is so far above my head that I feel like Charlie Brown......

It was pretty far above mine as well. It took me eight hours to figure out how to diagnose the problem and another four to diagnose it. Programming is not my thing so I Had to draw a line in the sand there.

BrentEvans wrote: ↑Thu Sep 24, 2020 11:09 am

Bruce Weldy wrote: ↑Thu Sep 24, 2020 10:13 am Brent, that is so far above my head that I feel like Charlie Brown......

It was pretty far above mine as well. It took me eight hours to figure out how to diagnose the problem and another four to diagnose it. Programming is not my thing so I Had to draw a line in the sand there.

That's why I stick to audio.....I'm just way too far behind to try and learn all the programming stuff. But, you are still young - so go for it!

Not as young as you think. I did two semesters of programming in college, 18 years ago. That was enough to teach me the programming is not my thing. I can make a hello world program in BASIC and C and that’s about it.

I did manage to learn a bit more about networking, which is how I diagnosed this issue. The OEM has submitted it to development as a bug, and I think the fact that I work for a dealer who sells a lot of these things does help me in that regard because they took me seriously and responded quickly, but the developers are in S Korea, and there’s no ETA on a firmware patch. In the meantime, a workaround would do... but this this post.

If you are tracking UDP packets, or any network packets, it all comes down how you want to 'intercept' and reroute those packets.

Typical layer 4 management becomes tricky if you are doing anything other than redirection. I've done packet monitoring and management before but never 'middleman' modification and that was on a mainframe which probably didn't care less about any anomalies in the packets.

Chris_Allen wrote: ↑Fri Sep 25, 2020 2:55 pm If you are tracking UDP packets, or any network packets, it all comes down how you want to 'intercept' and reroute those packets.

Typical layer 4 management becomes tricky if you are doing anything other than redirection. I've done packet monitoring and management before but never 'middleman' modification and that was on a mainframe which probably didn't care less about any anomalies in the packets.

Those are all good questions. What I know is that the control software I'm using (vMix) sends a UDP packet to the camera's IP on port 1259 containing the string "81 09 06 12 FF" and expects the response to be "y0 50 0w 0w 0w 0w 0z 0z 0z 0z FF" where 0w and 0z represent the pan and tilt position of the camera. What the camera is (erroneously) returning is "y0 50 0w 0w 0w 0w 0z 0z 0z 0z 0x 0x 0x 0x FF" where 0w and 0z values are correct but the 0x values represent the zoom position of the camera, which can be (and should be) queried with a different inquiry. As far as I can tell, all other inquiries are responding properly and could be "passed through" so to speak. Only this one string would have to be corrected.

There may be one or more cameras with IPs which would have to be definable in some way (a simple spreadsheet of IPs would be fine). I know windows has the ability to redirect ports through the command line... maybe that could be useful. Another thought I had was to somehow have a little server running which could establish a "dummy" IP for each camera and alter and pass the traffic through that way. I just don't know enough about it to know whether either idea is feasible or how to code it if it was.

And.. actually.. this inquiry is the longest reply the camera makes. most of the rest are just a few bytes. It could easily be a logic of "check all strings to make sure all traffic coming from this ip does not exceed 22 characters and make sure characters 21 and 22 are FF if the string reaches that length. If FF is detected in the string, stop checking."