Can S7 PLC send CLi commands

[Nuko-san]

Hi Guys,
Got an interesting question, has anybody tried to use a PLC to re-configure a router? I have done so using SNMP (relatively simple but not reliable) and was wondering whether anyone tried sending an SSID change "request"(for example).

 

[mk42]

Hi Guys,
Got an interesting question, has anybody tried to use a PLC to re-configure a router? I have done so using SNMP (relatively simple but not reliable) and was wondering whether anyone tried sending an SSID change "request"(for example).

I've never heard of anyone trying to send CLI commands over telnet/ssh from a PLC.



SNMP however, I've used multiple times. There is a library available on the Siemens website. Whatever you changed, always make sure you read the values back to make sure they took.



https://support.industry.siemens.com/cs/us/en/view/57249109


You would probably need a MIB browser to understand the OID structure, but at least with SCALANCE switches you can get a lot from the config file. Everything in the config file includes the OID, which can make a great starting point.

 

[andrewwei]

I've never heard of anyone trying to send CLI commands over telnet/ssh from a PLC.



SNMP however, I've used multiple times. There is a library available on the Siemens website. Whatever you changed, always make sure you read the values back to make sure they took.



https://support.industry.siemens.com/cs/us/en/view/57249109


You would probably need a MIB browser to understand the OID structure, but at least with SCALANCE switches you can get a lot from the config file. Everything in the config file includes the OID, which can make a great starting point.

Actually python can to send some values to some PLCs, Pymodbus, Pylogix. If you can access the PLC. Automation Direct PLC even allows more control over ethernet. Some day, some bad hacker is going to cause lots trouble.

 

[mk42]

Actually python can to send some values to some PLCs, Pymodbus, Pylogix. If you can access the PLC. Automation Direct PLC even allows more control over ethernet. Some day, some bad hacker is going to cause lots trouble.

That's totally a different scenario, though, interacting with a PLC from a CLI instead of interacting with a CLI from a PLC.



PLCs having networkable interfaces is a feature, not a bug; how else could you talk to an HMI? There are a bunch of libraries out there for all sorts of communication mechanisms across multiple PLC platforms, protocols, and communication languages. It does mean that you need to be careful about network security though, 100%.

 

[andrewwei]

I am not saying it is a bug. It is a door.