I have a project in which I need to monitor 4 digital inputs, and 4 analogue inputs.
I have a analogue to digital converter.
I need to send these through an Ethernet cable to a web server.
Sampling rate should be around 10k but this is not a hard limitation.
Any of the Arduino boards can probably collect 4 digital inputs and 4 analog inputs. The Arduino boards have an on-board 10 bit ADC with 6 (or more) inputs. If you want to know if an external ADC can be used then you need to provide a link to the datasheet for the device.
You can get an Ethernet shield for an Uno.
When you say 10k sapling rate, is that for all inputs combined (digital and analog) or is that for each input, all operating at 10k?
The biggest limitation may be the amount of SRAM in which to temporarily store the collected data. It may also be worth considering a RaspberryPi.