How could I network during my Phd? I am thinking a bit ahead of time and I would like to do some networking with some groups in my research field, for probably a future postdoc opportunity with them after my PhD. However I am afraid my supervisor prevents me to do that, she doesn't seem very happy with the idea of me doing some research stays somewhere else, or even going to conferences, and most likely she would connect me with anyone during and after my PhD, so how could I do some networking ??
I have a few suggestions.


Check out LinkedIn and join groups based on your field of interest. Simply having a profile and stating your field of study will help people find you. Comment on articles, or even write posts, because it will help people see your name. Don't be scared to message people you don't know.
If you have the money, let your supervisor know you're taking a week or whatever off and go to the conference yourself.
If you don't like the last point, look up speakers at conferences and point out ones to your supervisor that would be applicable and helpful for your studies. Remind her that it may bring you more insight or better ideas for your own work. Let her know that you can work on your studies during non-conference hours if necessary.
Watch for alumni events within your own faculty. If there are none, ask other professors or the department head if they know of any talks coming up that may be of interest. Just because you have a supervisor doesn't mean you can't talk to other professors.