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| − | =Installation=
| + | [[Category:Linux]] |
| | | | |
| − | By default Debian | Ubuntu doesn't include any SSH server.
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| − | <syntaxhighlight lang="bash">
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| − | apt-get install ssh openssh-server
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| − | </syntaxhighlight>
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| | | | |
| | + | =SSH client= |
| | | | |
| | | | |
| | + | ==Linux== |
| | | | |
| − | =SSH server configuration= | + | ===Standard login=== |
| − | | |
| − | | |
| − | Edit the configuration file:
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| | | | |
| | <syntaxhighlight lang="bash"> | | <syntaxhighlight lang="bash"> |
| − | vim /etc/ssh/sshd_config
| + | # syntax |
| − | </syntaxhighlight>
| + | ssh user@server -p portNumber |
| | | | |
| − | | + | # example |
| − | ==X11 forwarding==
| + | ssh root@daxiongmao.eu -p 4422 |
| − | | |
| − | In the configuration file, uncomment and set:
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| − | <syntaxhighlight lang="bash">
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| − | ForwardAgent yes
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| − | ForwardX11 yes
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| − | ForwardX11Trusted yes
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | '''Enable | Disable the forwarding:'''
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | # This server doesn’t have a XServer. Therefore do not forward graphical data.
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| − | X11Forwarding no
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | ==Port(s) number==
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| − | | |
| − | You can listen on multiple port. Just do the following:
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | Port 22
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| − | Port 2200
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | Security psycho mode:
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | # The default port SSH is 22. You may want to change that port to another one so your server will be more discreet.
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| − | # NB: if your server is hosted the provider might need access for maintenance purposes. | |
| − | Port XXXXX
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | | |
| − | ==Restart SSH server==
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | /etc/init.d/ssh restart
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | | |
| − | | |
| − | =SSH server configuration - Authentication by Linux user login / password=
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| − | | |
| − | ==Principle==
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| − | | |
| − | This is the default authentication system.
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| − | | |
| − | | |
| − | Each user that has a '''local account on the server''' and member is allowed to access the SSH server with its login / password.
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| − | | |
| − | [[File:SSH server default auth.png|none|SSH default authentication system]]
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| − | | |
| − | | |
| − | | |
| − | ==Configuration changes==
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | vim /etc/ssh/sshd_config
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | ===Protocol and password enforcement===
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | Protocol 2 # only use SSH v2
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| − | PermitRootLogin no # Avoid root connections
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| − | PermitEmptyPassword no # Forbidden user with empty passwords
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | ===Login time===
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | # Time to log
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| − | LoginGraceTime 30
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | ==Restart SSH server==
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | /etc/init.d/ssh restart
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | | |
| − | | |
| − | | |
| − | =SSH server configuration - Authentication with RSA keys=
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| − | | |
| − | | |
| − | ==Introduction==
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| − | | |
| − | If you’d like to increase the authentication process you can use authentication by private/public key.
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| − | * Generate new private / public keys on your own computer
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| − | * Put the public key on the remote SSH server
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| − | * Only the person with the private key can be authenticate on the server
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| − | | |
| − | | |
| − | [[File:SSH_server_RSA_keys.png|none|SSH RSA authentication]]
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| − | | |
| − | | |
| − | | |
| − | For instance, this is how hosting company such as OVH can log on your system.
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| − | | |
| − | | |
| − | | |
| − | '''Security improvement: remove password authentication'''
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| − | | |
| − | When the key authentication is working you can remove the default access by login / password.
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| − | Then, only people with a valid private/public key pair can log in.
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| − | | |
| − | That way, there is no way for brute-force attacks to be successful, so your system is more secure.
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| − | | |
| − | | |
| − | | |
| − | ==Declare the public key on the server==
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| − | | |
| − | | |
| − | You have to:
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| − | * '''log in''' to your SSH server with the '''user that’s gonna use this key'''
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| − | * Go to '''user's home''' directory
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| − | * Create a '''.ssh''' folder (if there was none before).
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | cd ~
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| − | mkdir .ssh
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| − | cd .ssh
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| | </syntaxhighlight> | | </syntaxhighlight> |
| | | | |
| | | | |
| − | Add the new ''public'' key to the list of allowed keys:
| + | ===Using RSA key=== |
| − | | |
| − | <syntaxhighlight lang="bash">
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| − | vim authorized_key2
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | Prefix your key with:
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| − | * RSA: ssh-rsa
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| − | * DSA: ssh-dss
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| − | | |
| − | Then paste the public key in one line - the public key mustn't be change or separated in 2 lines!
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| | | | |
| | + | Key points: |
| | + | * The key must belongs to the current user |
| | + | * The key rights must be "500" |
| | | | |
| − | <syntaxhighlight lang="bash">
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| − | # Example:
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| − | ssh-rsa AAAAB3NzaC1yc2EA[...]Lg5whU0zMuYE5IZu8ZudnP6ds= myname@example.com
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| − | ssh-dss AAAAB3NzaC1yc2EA[...]Lg5whU0zMuYE5IZu8ZudnP6ds= myname@example.com
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| − | </syntaxhighlight>
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| | | | |
| − | | + | Then you can log-in using the following command: |
| − | Adjust file rights, the ''authorized_keys2'' file must be write/readable only by that user
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| | | | |
| | <syntaxhighlight lang="bash"> | | <syntaxhighlight lang="bash"> |
| − | chmod 600 authorized_keys2
| + | ssh -i Guillaume_OpenSSH.private -p 2200 guillaume@dev.daxiongmao.eu |
| − | cd ..
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| − | chmod 700 .ssh
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| | </syntaxhighlight> | | </syntaxhighlight> |
| | | | |
| | + | Where: |
| | + | * '''-i''' ''myFile'' = the private key you have to use |
| | + | * '''-p''' ''port'' = specific port number (if not default 22) |
| | | | |
| | | | |
| | | | |
| − | | + | ===X11 forwarding=== |
| − | ==Configuration changes== | |
| | | | |
| | <syntaxhighlight lang="bash"> | | <syntaxhighlight lang="bash"> |
| − | vim /etc/ssh/sshd_config
| + | ssh -X guillaume@nuc-media-center |
| | </syntaxhighlight> | | </syntaxhighlight> |
| | | | |
| | | | |
| − | ===Protocol and password enforcement===
| + | ♦ Note that the remote computer have X11 installed and X11 applications. |
| − | | |
| − | | |
| − | | |
| − | | |
| − | | |
| − | | |
| − | ==Restart SSH server==
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | /etc/init.d/ssh restart
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | Requirements – windows
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| − | Download the following software:
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| − | • PuTTY
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| − | • PuTTYgen
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| − | • Pageant
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| − | | |
| − | | |
| − | Windows - Generate new private / public keys pair
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| − | Start PuTTYgen
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| − |
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| − | | |
| − | Create a 4096 bits key, DSA algorithm.
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| − | | |
| − |
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| − | | |
| − | Then, click on generate
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| − | When the keys are OK, you have to enter a key passphrase.
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| − | You passphrase must be long (> 15 characters), hard to guess, with letters + signs + numbers
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| − | | |
| − | Reminder: how to choose your passphrase and protect it:
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| − | http://www.alcf.anl.gov/resource-guides/user-authentication-policies
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| − | | |
| − | Then, save your keys!
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| − | You should be the only one to access the save location.
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| − | | |
| − |
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| − | Declare the public key on the server
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| − | You have to log in to your SSH server with the standard user that’s gonna use this key.
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| − | Go to your home directory, and create a .ssh folder (if there was none before).
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| − | # cd ~
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| − | # mkdir .ssh
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| − | # cd .ssh
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| − | # vim authorized_key2
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| − | | |
| − | Prefix your key with:
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| − | RSA: ssh-rsa
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| − | DSA: ssh-dss
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| − | Then paste the public key into the file in one line!
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| − | | |
| − | Copy the text as shown on the previous image.
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| − | | |
| − | Example:
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| − | ssh-rsa AAAAB3NzaC1yc2EA[...]Lg5whU0zMuYE5IZu8ZudnP6ds= myname@example.com
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| − | ssh-dss AAAAB3NzaC1yc2EA[...]Lg5whU0zMuYE5IZu8ZudnP6ds= myname@example.com
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| − | | |
| − | Adjust file rights
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| − | The authorized_keys2 file must be write/readable only by that user
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| − | | |
| − | # chmod 600 authorized_keys2
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| − | # cd ..
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| − | # chmod 700 .ssh
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| − | | |
| − | Windows – configure PuTTY client
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| | | | |
| − | You have to configure your PuTTY SSH client with this new key.
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| | | | |
| − | Create profile
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| − |
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| − | Auto-login
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| − |
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| | | | |
| | + | ==Windows== |
| | | | |
| | + | You have to use Putty to perform SSH login. |
| | | | |
| − | Attach private key
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| − |
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| | | | |
| − | Save profile
| + | '''How to add a public / private key in Putty ?''' |
| − | Go back to the main screen Session and save your changes.
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| − |
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| | | | |
| − | Click on “open” to initialize connection.
| + | 1.Create profile |
| | | | |
| − | Login procedure
| + | [[File:Putty_SSH_access_1.png|none|Putty SSH login step 1]] |
| | | | |
| − | Type your passphrase on system request
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| − |
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| − |
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| − | Access is granted!
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| − |
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| − | Disable standard username / password login
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| − |
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| − | Edit the configuration file
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| − | # vim /etc/ssh/sshd_config
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| − |
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| − | Adjust the line:
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| − |
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| − |
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| − | to:
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| − |
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| − |
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| − | Restart SSH server:
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| − | # /etc/init.d/ssh restart
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| − |
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| − | OVH server: root access
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| − |
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| − | OVH requires a root access for maintenance.
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| − | OVH uses a RSA key for authentication. You have to let the following settings:
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| − | SSH port : 22
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| − | Root login : enable
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| − | UsePam: yes
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| − |
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| − |
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| − | Important
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| − | If this access is removed then OVH will stop your server in case of DoS.
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| − | More details: http://guide.ovh.com/InstallClefOVH
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| − |
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| − | =Fail2ban=
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| − |
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| − | see [[Fail2ban#SSH_configuration]]
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| − |
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| − |
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| − | =SSH client=
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| − |
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| − |
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| − | ==Linux==
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| − |
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| − | <syntaxhighlight lang="bash">
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| − | # syntax
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| − | ssh user@server -p portNumber
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| − |
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| − | # example
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| − | ssh root@daxiongmao.eu -p 4422
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| − | </syntaxhighlight>
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| | | | |
| | + | 2. Auto-login |
| | | | |
| | + | [[File:Putty_SSH_access_2.png|none|Putty SSH login step 2]] |
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| | | | |
| | + | 3. Attach private key |
| | | | |
| − | =References=
| + | [[File:Putty_SSH_access_3.png|none|Putty SSH login step 3]] |
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| | | | |
| − | Source: http://www.howtoforge.com/ssh_key_based_logins_putty
| + | 4. Save profile |
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| − | Windows - putty software: http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html
| + | [[File:Putty_SSH_access_4.png|none|Putty SSH login step 4]] |
