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| '''Secure Shell''' ('''SSH''') is a protocol that enables remote access to a server. It encompasses both the client-side application (`ssh`) and the server-side daemon (`sshd`). The most common implementation for Linux and BSD is '''OpenSSH'''. | '''Secure Shell''' ('''SSH''') is a protocol that enables remote access to a server. This is primarily a Linux and BSD feature, with Windows systems preferring access by [[RemoteDesktopProtocol|RDP]]. The most common implementation is the '''OpenSSH''' project. The server-side service is `sshd(8)`, while there are various client-side programs such as `ssh(1)` or PuTTY. <<TableOfContents>> |
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| == Setup == | == Installation == |
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| On Linux, `sshd` runs by default. On BSDs, you will need to enable it. In `/etc/rc.conf`: | === Client === If necessary, install `openssh`. Most Linux and BSD distributions will include it by default. On Windows, try PuTTY and hope it works. === Server === Many Linux distributions have `openssh` installed and `sshd(8)` running by default. This is especially true of ISOs meant for server boxes. For `systemd(1)`-capable systems, [[Linux/Systemd|start and enable]] `sshd.service`. For `init`-based systems, try `service sshd enable` or setting the following in `/etc/rc.conf`: |
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| == Require Authentication by Key == | == Configuration == |
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| To require that all logins use keys, use: | === Require Authentication by Key === To require that all client logins use keys, use: |
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| Match user git | Match User git |
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| Match address 192.168.*.* PAsswordAuthentication yes |
Match Address 192.168.*.* PasswordAuthentication yes |
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| ---- | |
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| === Login Messages === | |
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| == Login Messages == | Usually any messages printed on login are actually handled by PAM. This can be tricky to configure, so instead disable the default login messages and configure the shell profile to print the desired messages. |
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| Usually any messages printed on login are actually handled by PAM. This can be tricky to configure, so instead disable all login messages and recreate any desired messages. To disable all PAM login messages for a user, just: |
To disable all PAM login messages for a user, try: |
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| Default PAM configurations print `/etc/motd` and the output of `/usr/bin/lastlog --user USERNAME`. These can just as easily be added to `~/.bashrc`. | Note that default PAM configurations print `/etc/motd` and the output of `/usr/bin/lastlog --user USERNAME` on login. |
SSH
Secure Shell (SSH) is a protocol that enables remote access to a server. This is primarily a Linux and BSD feature, with Windows systems preferring access by RDP. The most common implementation is the OpenSSH project.
The server-side service is sshd(8), while there are various client-side programs such as ssh(1) or PuTTY.
Installation
Client
If necessary, install openssh. Most Linux and BSD distributions will include it by default.
On Windows, try PuTTY and hope it works.
Server
Many Linux distributions have openssh installed and sshd(8) running by default. This is especially true of ISOs meant for server boxes.
For systemd(1)-capable systems, start and enable sshd.service.
For init-based systems, try service sshd enable or setting the following in /etc/rc.conf:
sshd_enable="YES"
Configuration
Require Authentication by Key
To require that all client logins use keys, use:
PubkeyAuthentication yes AuthorizedKeysFile .ssh/authorized_keys PasswordAuthentication no
To make an exception for a user, add at the bottom of the file:
Match User git PasswordAuthentication yes Match all
To make an exception for the local network, add (also at the bottom of the file):
Match Address 192.168.*.* PasswordAuthentication yes Match all
Login Messages
Usually any messages printed on login are actually handled by PAM. This can be tricky to configure, so instead disable the default login messages and configure the shell profile to print the desired messages.
To disable all PAM login messages for a user, try:
touch ~/.hushlogin
Note that default PAM configurations print /etc/motd and the output of /usr/bin/lastlog --user USERNAME on login.