![]() ![]() I've got some feedback that it is unnecessary to disable this since users with sudo permissions could do the same damage, but I disagree. Prohibits connecting as root as it is recommended to work with a separate user with optional sudo permissions. Just make sure to avoid conflicts with already used ports. Side note: choosing a port below 1024 (system or well-known port) is recommended to make it more difficult for an unprivileged user to highjack the service, as by default, non-root processes can only open ports above 1023. Adds complexity, as clients and scripts must be configured differently, must be documented, users must be informed, etc.Compatibility issues, since some clients or applications might not work with a non-default port.It does not protect against targeted attacks, as a simple port scan can detect the correct port.Great for internal servers as port scans are uncommon for internet-facing servers, rather useless as port scans are inevitable and common Attackers need to port scan to find the correct port, which makes it easier to detect targeted attacks with IPS and firewalls.Reduce exposure to automated attacks and bots.There is no perfect answer, but I hope the following list of pros and cons will help you to decide: Some people think it is a must some think it is useless. Changing the ssh port #Ĭhange the default SSH port 22 of your host to something else. It requires some configuration on the server and client, but it is worth it as it is one of the best ways to protect your server. I highly recommend securing your server with public key authentication instead of password authentication.Īfter enabling it, make sure to turn off password authentification: ![]() You can find a guide on how to use public key authentication in this linked article. Use sudo sshd -T for a more verbose output, which additionally displays all the options that are used.Īlmost every config file change requires a restart of the SSH server service. etc/ssh/sshd_config: terminating, 1 bad configuration options etc/ssh/sshd_config: line 49: Bad configuration option: DebianBanner That said, you can check the configuration file with sudo sshd -t no output means that it is okay, and errors will be displayed if someone is not working out, like in the following example: Just make sure that the default configuration file references the subdirectory with Include /etc/ssh/sshd_config.d/*.conf. Side note: It is recommended to create a separate configuration file as the default file is at risk of getting overwritten with a future software update. The following configurations can be changed in the /etc/ssh/sshd_config file or in a separate configuration file that can be created in a subdirectory /etc/ssh/sshd_config.d/*.conf. Important: Please test the configuration changes in a test environment or a single user or group to limit the lockout risk!Īdditionally, DO NOT copy any configuration mindlessly! - Some configuration changes are just recommendations and work in most cases, but make sure those work for your system, too. I'll use Linux with an SSH server as a reference ( OpenBSD Secure Shell server according to systemd). This article covers mainly the configuration of the SSH service and only references ways to protect the service on the host machine or via policies. This is an updated version from last year.
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