I have a website that authenticates users with the active directory. This website is made for internal company use and does not hold any sensitive information. The website is secured with SSL. When a user logs in, his/her username and password will be transmitted to the server through POST. I then store his/her username in a session cookie with a TTL of 1 day, refreshed by every single web action. From this point on, every webpage will check to see if this cookie with the username exists. If it does, it will allow users to access that certain page. Login out will just remove this cookie.
Would this way of authentication be acceptable? Is there a better way to handle user authentication? Is it necessary to use sessions instead and store session id's in cookies?