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https://github.com/authy/authy-ssh

Easy two-factor authentication for ssh servers
https://github.com/authy/authy-ssh

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Easy two-factor authentication for ssh servers

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README 

        
# Authy SSH



## Pre-requisites.



1. Authy API Key: https://www.authy.com/signup



## Installation.



Type the following command in the terminal:



    $ curl -O 'https://raw.githubusercontent.com/authy/authy-ssh/master/authy-ssh'

    $ sudo bash authy-ssh install /usr/local/bin



Then enable two-factor for your user:



    $ sudo /usr/local/bin/authy-ssh enable `whoami`   



Test everything is working:



    $ authy-ssh test



Restart your SSH server (look below if you are not on Ubuntu).



    $ sudo service ssh restart



##### Restarting your ssh server



**Ubuntu**



    sudo service ssh restart



**Debian**



    sudo service sshd restart



**RedHat and Fedora Core Linux**



    sudo /sbin/service sshd restart



**Suse linux**



    sudo /etc/rc.d/sshd restart



###  Installing without root privileges.



Type the following command in the terminal:



    $ curl 'https://raw.githubusercontent.com/authy/authy-ssh/master/authy-ssh' -o authy-ssh

    $ bash authy-ssh install ~/.authy-ssh/



Now protect your user:



    $ bash ~/.authy-ssh/authy-ssh protect



## Enable two-factor auth on a user.



After the installation is finished, you have to proactively enable the two-factor for the users you want to protect.



To enable users type the following command and fill the form:



    $ sudo authy-ssh enable



If you want to do it in one line just type:



    $ sudo authy-ssh enable    



## How it works



Authy-ssh uses the `sshd_config` directive `ForceCommand` to run itself before every login. Here's how your sshd_config will look after installing:



    [root@ip-10-2-113-233 ~]# cat  /etc/ssh/sshd_config | grep ForceCommand

    ForceCommand /usr/local/bin/authy-ssh login

]

Whenever  it  runs authy-ssh will read it's configuration from /usr/local/bin/authy-ssh.conf

Here's an example:



    [root@ip-10-2-113-233 ~]# cat /usr/local/bin/authy-ssh.conf

    banner=Good job! You've securely logged in with Authy.

    api_key=05c783f2db87b73b198f11fe45dd8bfb

    user=root:1

    user=daniel:1



In this case it means user root and daniel have two-factor enabled and that 1 is their `authy_id`. If a user is not in this list, `authy-ssh` will automatically let him in.



## Using two-factor auth with automated deployment tools.



If you use **capybara**, **chef**, **puppet**, **cfengine**, **git** you can create new users for these tools so they can enter the machine without requiring two-factor.

Alternatively, you can match users using the `ForceCommand` directive.



A good example is create a two-factor users group.



    groupadd two-factor

    usermod  -a -G two-factor root



Now that my root user is in the two-factor group, I edit my /etc/ssh/sshd_config



    [root@ip-10-2-113-233 ~]# cat /etc/ssh/sshd_config | grep ForceCommand -A 1 -B 1

    match Group two-factor

        ForceCommand /usr/local/bin/authy-ssh login



	$ /sbin/service sshd restart

    Stopping sshd:                                             [  OK  ]

    Starting sshd:                                             [  OK  ]



Now force command will only operate on users that belong to the two-factor group.



## `scp`, `sftp`, `mosh` and `git push` with two-factor authentication.



To enable non-interactive commands like `scp`, `sftp`, `mosh` and `git clone|fetch|push` you have to allow to pass the environment variable `AUTHY_TOKEN` from the client. To do so edit your `sshd_config` (normally located at `/etc` or `/etc/ssh/`) and add `AUTHY_TOKEN` to the AcceptEnv directive:



	AcceptEnv AUTHY_TOKEN



Then configure the client to send that variable to the server, to do so first open `~/.ssh/config` and then add the following:



	Host *

		SendEnv AUTHY_TOKEN



And finally pass the token before the command:



    AUTHY_TOKEN="valid-token" git push origin master

    AUTHY_TOKEN="valid-token" scp server:path/to/file local-file

    AUTHY_TOKEN="valid-token" mosh server



### Note



For cases like `sftp` if you enter an invalid token, you may receive a response like *"Received message too long 458961713"*. This is because the interactive command is not able to render the proper output text message returned by the program.



## Multiple users sharing the same unix account.



If you have many users that need to share a single login, you can still use strong two-factor authentication without sharing the same token. This means that every user can have their own Authy Token, ensuring non-repudiation.



To achieve this, delete or comment out the `ForceCommand` directive from your `sshd_config`:



	$ sudo sed -ie 's/^\(ForceCommand.*authy-ssh.*\)/#\1/g' /etc/ssh/sshd_config



and then for each person add their ssh key using the following command:



	$ sudo authy-ssh protect



you should end up with an authorized_keys file that looks like:



	command="/usr/local/bin/authy-ssh login 13386" ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDGRJbWu+WLVXYVADY3iQPE1kA7CIOSqHmskPM8qIAzKzq+1eRdmPwDZNmAvIQnN/0N7317Rt1bmTRLBwhl6vfSgL6677vUwsevPo27tIxdja67ELTh55xVLcJ3O8x2qkZsySgkLP/n+w3MUwLe1ht31AZOAsV7J7imhWipDijiysNgvHyeSWsHqExaL1blPOYJVHcqPbKY4SxFRq/MWeyPf/Sm24MFSKEaY6u0kNx8MLJ1X9X/YxmY9rdvzsZdQ7Z/PYhYt2Ja/0mzfYx2leeP2JQBsVfZZzAoFEPpw6mSP9kJREGe2tXvS9cRenhz/+V0+mvSJKG0f0Zzh428pTzN

	command="/usr/local/bin/authy-ssh login 20" ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAyvj2d0rSDukDT04mK7njUxtXffUrOnDCm2Bqub0zN7LQS733nBHp89aMuBI5ENjw1SQ2qXhLxvK1Xhr0pQr+dOWNn3emQjQuiA+YL39yp2RLLpflerJ3KAVY09CHYLFxdKj/DJgXsH+LMAPe2uVmWCP2xAV5ZcLnz3CdS2SX/EVlbNrftesZx9uAbmwKPLY1pmW7q/75AhJRow8VTP7zM/VS7jEHkj03g51BZGB8tMI3G8RDVEDtu2jVwZiq+8BaNCyjYVlsLfu6uGhnXeeUS3swu/atlt+pxy+QTf/HGvrJR58tER+foqheWtV3LqXN4oLckzqTVkDDmnNJlmrpYQ==



The previous command will ask you the user ssh public key, cellphone and email.



## Uninstall



To uninstall type:



    $ sudo authy-ssh uninstall

    $ restart your SSH server



## Running Unit Tests



Fork and clone the git repository https://github.com/authy/authy-ssh.git



    $ cd tests

    $ rake test