If you are managing the Ubuntu server, you can use the following tools on Windows 8 to connect and manage your Ubuntu server remotely.
Putty is a simple console which allows us to connect to remote server using SSH protocol.
Putty supports Raw, Telnet, Rlogin, SSH and Serial protocols. You can grab this free application from the official website.
WinSCP is also uses SSH protocol which can be used to connect to remote Ubuntu server from Windows 8. The advantage of WinSCP is the built in file browser. We can browse the files stored on Ubuntu server directly from WinSCP. We can also upload or download files to the server from Windows 8 vice versa.
Grab WinSCP for Windows for free from this website.
3. Bitvise SSH Client for Windows
Same with Putty, Bitvise SSH Client offers a secure and easy way to connect to remote Ubuntu server. Bitvise SSH Client is free for personal use. And if you need more features such as file transfer and tunneling, you can purchase the pro version.
The advantage of using Bitvise SSH Client is to have both type of interface. I mean, we have a text based console like Putty and also we have a file browser like WinSCP. So Bitvise SSH Client is the combination between Putty and WnSCP. Two features in single app.
Grab Bitvise SSH Client for Windows from the official website.