I'm trying to access my RPi 3 via Putty from a Windows 10 laptop. When it prompts me to choose the user I type in pi. I have tried typing in raspberry as the password, resetting the password with sudo passwd and trying with that password but nothing works. BTW I have already placed a file named ssh in the boot partition of my Pi so that it automatically boots with ssh on. I'm using NOOBS 2.1.0.
Is this your first time trying to SSH into the Raspberry Pi? I did this a couple of days ago, and manually changed the Pi's configuration from the GUI interface to allow for SSHing, then rebooted.
In case you haven't seen it, here's the official documentation https://www.raspberrypi.org/documentation/remote-access/ssh/
To begin first of all you should NOT be using a the pi while connected to the internet with open ssh ports and default credentials allowed, this is madness. Your machine is likely already compromised in the worst case and will be after not to long in the best case.
Step 1. Reformat the sd card and reboot the pi ideally with a screen and keyboard, or if thats not possible then i would suggest doing the following quickly. https://www.raspberrypi.org/documentation/installation/installing-images/
Step 2. Boot the os either ideally with no internet and begin by adding a new user
sudo adduser username
Add the new user to sudo privilages,
Under root or pi add your username and permissions
%root ALL=(ALL:ALL) ALL username ALL=(ALL:ALL) ALL
Step 3. you want to configure and allow ssh connections either from the gui menu, adding the ssh file to the sd card before boot or using
now you want to edit the sshd config file to deny certain users and allow others
sudo nano /etc/ssh/sshd_config
There are many options but the bare minimum here would be
AllowTcpForwarding yes CHANE TO AllowTcpForwarding no X11Forwarding yes CHANGE TO X11Forwarding no PermitRootLogin no DenyUsers pi AllowUsers username
You should also consider either, changing the default pi users password to something long and secure (my suggestion) or deleting the pi account entirely. But the above should be the bare minimum to securing your raspberry pi and only allowing access to you, not everyone.
Ideally you might look at ssh keys for access instead