Dropbox announced Tuesday that a recent security breach compromised a list that included the email addresses of certain Dropbox users. To avoid future complications, the service announced that it would be implementing two-factor authentication, and even more useful, a security page that lets you monitor all activity on your account.
In light of this and other recent web security threats, you might also want to know that services like Gmail, Facebook, and Yahoo! Mail have similar pages where you can see who else might be accessing your account.
At the bottom of your Gmail window, you will see a footer that looks like this:
Here you will see when your account was accessed last. By clicking on details, you will see a list of when and where, including the IP address. If your account is open in another location, that will be displayed here, as well. If you are ever unsure if the computers listed are yours or not, you can always hit "Sign out all other sessions" to log out everyone.
To access a similar feature in Facebook, click on the dropdown menu in the upper right corner, next to your name. Select Account Settings.
Then select Security, and on that page, click the edit button next to Active Sessions.
This page will show you the time, browser, and approximate location of active sessions. Click on End Activity next to any of these to log that session out.
To see your activity in Yahoo! Mail, go to the link below:
Enter in your Yahoo Mail ID and password to log in and view your Account Information page. Then scroll down and click on "View your recent sign-in activity" under the Sign-in and Security section.
In any of these cases, whether it be Dropbox, Gmail, Facebook, or any other service, if you notice any suspicious activity, it's best to change your password as soon as possible.