Two Factors Authentication With OpenSSH
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Do not follow instructions here until this notice is removed.
Using Google Authenticator
# basic PAM configuration for Alpine. auth required pam_env.so #auth required pam_unix.so nullok_secure auth required pam_nologin.so successok auth required /lib/security/pam_google_authenticator.so
UsePAM yes AuthenticationMethods publickey,keyboard-interactive ChallengeResponseAuthentication yes PermitRootLogin yes
As user root:
Do you want authentication tokens to be time-based (y/n) y https://www.google.com/<pruned> Your new secret key is: <secret> Your verification code is <pruned> Your emergency scratch codes are: <pruned> <pruned> <pruned> <pruned> <pruned> Do you want me to update your "/root/.google_authenticator" file? (y/n) y Do you want to disallow multiple uses of the same authentication token? This restricts you to one login about every 30s, but it increases your chances to notice or even prevent man-in-the-middle attacks (y/n) n By default, tokens are good for 30 seconds. In order to compensate for possible time-skew between the client and the server, we allow an extra token before and after the current time. If you experience problems with poor time synchronization, you can increase the window from its default size of +-1min (window size of 3) to about +-4min (window size of 17 acceptable tokens). Do you want to do so? (y/n) y If the computer that you are logging into isn't hardened against brute-force login attempts, you can enable rate-limiting for the authentication module. By default, this limits attackers to no more than 3 login attempts every 30s. Do you want to enable rate-limiting (y/n) n
Download Google Authenticator app and enter manually your <secret> key