Gerrit,
I don’t think there is a way to setup authentication parameters via the UI. OS expects the contents of the server field in the UI to be either a simple server name or ip address, i.e. 192.168.1.210. It does not have code to parse the user:pass elements. I had a hand in writing this bit of the code so apologies for not making it more extensible to authentication.
If you are comfortable changing the firmware code and rebuilding then there may be a way to hardcode the user:pass details into the firmware by modifying a line in function switch_httpstation() in file OpenSprinkler.cpp ((line 1172 in current version):
From: ether.browseUrlRamHost(PSTR(“/”), cmd, server, httpget_callback);
To: ether.browseUrlRamHost(PSTR(“/”), cmd, server, PSTR(“Accept: text/html\r\nAuthorization: Basic dXNlcjpwYXNz”), httpget_callback);
Where dXNlcjpwYXNz is the base64 encoding of user:pass string which you can get via one of the online converters (google “base64 encode” – https://www.base64encode.org/)
Unfortunately, I can’t test this (I dont have an http station requiring authentication) but it “may” work. Obviously, it is somewhat limited if you have multiple http stations with different usernames/passwords. Ray may have a better answer but I am curious if this works 8)