I've recently tried moving an ASP.NET core 3.0 application from a windows server to a Linux server. The application shares cookie authentication with another website so the cookie domain needs to be a wildcard to share across the sub-domains i.e. .example.com
This works fine on the Windows server the cookie domain for https://sub.example.com gets set as .example.com
However, when I login on the Linux server the cookie domain for some reason gets set with the sub-domain. For example for https://sub-test.example.com the cookie domain is .sub-test.example.com, which then won't be shared with https://sub.example.com, hence the problem.
I've checked the network tab in the browser and the set-cookie header has "domain=.sub-test.example.com", so I'm convinced it's a server side problem.
In Startup.cs, I have hard coded the domain wildcard I want, it just doesn't get honoured on Linux.
services.ConfigureApplicationCookie(opt =>
{
opt.Cookie.Domain = ".example.com";
}
Not sure what else I can try.