[Ros2] Creating a UDP socket in a node

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I agree with gvdhoorn, I would suggest using boost::asio if you are familiar with it (install it manually if you dont have it already). Also, there seem to be some problems with just asio. For example, on Ros Index you can find this regarding Windows 10:

CMake Packages Unable to Find asio, tinyxml2, tinyxml, eigen, or log4cxx
We’ve seen, but been unable to identify the root cause, that sometimes the chocolatey packages for asio, tinyxml2, etc. do not add important registry entries and that will cause CMake to be unable to find them when building ROS 2.
It seems that uninstalling the chocolatey packages (with -n if the uninstall fails the first time) and then reinstalling them will fix the issue.

Here is an example CMakeLists.txt of me using boost:asio with ROS2.

find_package(Boost REQUIRED COMPONENTS system)

target_link_libraries(your_node ${PROJECT_NAME} ${Boost_LIBRARIES})

ament_export_dependencies(Boost)
ament_export_libraries(${PROJECT_NAME} ${Boost_LIBRARIES})

For the UDP socket implementation within ROS/ROS2 I have used this so far.

ROS 2 no longer has boost as a dependency and recommends using the std library in C++ to replace most of the boost classes and functions

the recommendation would be to use std:: as much as possible, but there are of course situations in which that is impossible (such as the one you find yourself in).

Boost is in no way deprecated, nor are you "forbidden" from using it (or is it made any harder to use Boost in ROS 2 than it is/was in ROS 1).

So my question is, how can I make nodes send and receive data in ROS 2 without boost? I noticed on Windows 10, asio was a dependency and I was wondering if I can just use asio, [..]

There are quite a few socket libraries for C++ other than boost::asio, but if you're familiar with it then I would suggest to just keep using it.

how do I include it and declare it as a dependency in my node?

In exactly the same way as you would do it in ROS 1: by stating it in your package.xml -- dependency declarations haven't changed, and as Boost was never a Catkin package, you'd even still use find_package(Boost REQUIRED COMPONENTS ..).

The same rosdep key is used (ie: boost, or asio for the standalone version).