Orange Pi Zero is cheap (7$ + shipping), can be hacked to run on passive PoE, supports TCP/UDP over on-board ethernet and wireless and has a few I/Os.
It's not exactly a microcontroller in my book, it's more like a small headless linux computer, but then you mention raspberrypi zero as a reference which is in the same class.
When using it, be sure to use ...
The simplest solution is to add an external ethernet interface driven over SPI, as used in this example.
It's also possible to bit-bang the ethernet interface directly, as decsribed in this article, Ethernet Controller Discovered in the ESP8266. Performance might not be as good as with a dedicated interface though.
Neither of these include Power over ...
You do not need PoE for your setup. Just use two wires from Ethernet cable to power your controllers.
Ethernet cables have four unused wires: 4 (blue), 5 (white with blue), 7 (white with brown) and 8 (brown). For personal use, I believe, you can use these wires for powering up your micro controllers. Of course, you should take precautionary measures in case ...
The ESP8266 was not designed with an Ethernet MAC, but this should not stop you. However, as Sean has said, it imposes a set of pretty severe restrictions on you.
You say that you wish to stay with the ESP8266 platform, but if your project cannot deal with the measly data rates provided by using an ENC28J60-style chip, or bit-banging Ethernet, then there ...
Arduino do a board with built in PoE, but at double the price of a Pi last time I looked, I would not consider it cheap. And sounds physically bigger than you are looking for.
The is also the Arduino Yun with poe, but that costs even more
If a pi Zero W will do what you want you can get PoE adapters for of the order of £8 each singularly, possibly cheaper ...
Well, I am a big fan of the Omega 2, which is not much bigger than a full size SIM card or SD card. It runs Linux, so there is your TCP/IP stack.
It has a good spec and will set you back a whopping $13.
580MHz MIPS CPU
2.4GHz b/g/n WiFi
3.3V Operating Voltage
Support for UART, I2C, SPI
Just by ...
The program MJPG_streamer has an UDP option. This program is commonly used with DIY security cameras running embedded Linux. This program does not allow motion detection however. You must sync the stream to a monitoring program such as Zoneminder. The motion detection program Motion also allows UDP, but mentions this: The TCP transport is highly preferred ...
If you are sure about using ARM then you could have a look at Keil's Ethernet Drivers for ARM. It is quite promising.
RL-TCPnet includes several Ethernet Network drivers. These are
located in the \Keil\ARM\RL\TCPnet\Drivers directory:
LAN91C111.C - for the SMSC LAN91C111 Ethernet Controller used on the Phytec phyCore LPC229x evaluation board.
It's a bit hard to tell what you're looking for when you ask for bare metal, particularly when you don't specify the architecture...
For an embedded application, using a lightweight OS (depending what you regard as an OS), look at the mbed source for a device similar to the one you're interested in (assuming an ARM Cortex-M microcontroller).
The latest ...
I was using Itead Iboard arduino based ethernet board, powered by passive PoE adapter. I bought them for 14$ each, poe adapters can be purchased for less than $1 on ebay. Since it is MCU based, it boots instantly, doesn't require SD card, totally safe and cannot be hacked. I use it for home weather monitoring system using both TCP and UDP protocols with ...
I list microcontrollers up to 30 EUR here. I'll keep looking and update this if I find something interesting. A really good solution would be something below 10 EUR, but I haven't found anything like that.
The Lantronix XPort is 30 EUR + shipping, in theory that would work too, but the prices are interesting, they are between 20 and 200 EUR, so hard to tell ...
As @MaxDZ8 says, your question is very broad, but I'd like to encourage you, and this is something I'm also interested in.
You should start small, perhaps with a simple system.
You've mentioned an IP-camera, and the Pi 3 can certainly do that, for example:
Build a Raspberry Pi Webcam Server in Minutes
(see Setting up outside External Access)
Regarding your ...
The given settings in /etc/config/network are correct. However, to apply the settings, it isn't sufficient to restart the network via /etc/init.d/network restart but also applying the DNS servers via /etc/init.d/dnsmasq restart which had not been done. After that, the Onion Omega2 is able to connect to the internet via its ethernet connection.