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	"title": "What is SSH (Secure Shell)? | SSH Academy",
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	"plain_text": "What is SSH (Secure Shell)? | SSH Academy\r\nBy Admin\r\nPublished: 2019-08-27 · Archived: 2026-04-05 17:52:18 UTC\r\nThis is the start page for the SSH (Secure Shell) protocol, software, and related information. SSH is a software\r\npackage that enables secure system administration and file transfers over insecure networks. It is used in nearly\r\nevery data center and in every large enterprise.\r\nThis page was created by the inventor of SSH, Tatu Ylonen (twitter: @tjssh). He wrote ssh-1.x and ssh-2.x, and\r\nstill works on related topics. The open source OpenSSH implementation is based on his free version.\r\nThe SSH protocol\r\nThe SSH protocol uses encryption to secure the connection between a client and a server. All user authentication,\r\ncommands, output, and file transfers are encrypted to protect against attacks in the network. For details of how the\r\nSSH protocol works, see the protocol page. To understand the SSH File Transfer Protocol, see the SFTP page.\r\nDownload client software\r\nhttps://www.ssh.com/ssh\r\nPage 1 of 4\n\nHere you can find links to download various free SSH implementations. We offer various free SSH\r\nimplementations for download, and provide links to commercial implementations.\r\nDownload PuTTY\r\nDownload SSH clients\r\nList\r\nof SSH implementations\r\nWe list various SSH implementations here. Feel free to submit additional implementations for this page. For many\r\nimplementations we offer a review, installation instructions, guidance, and/or how-tos on this site.\r\nTectia SSH client \u0026 server for Windows, Unix, Linux - with 24x7 support\r\nTectia SSH for IBM z/OS client \u0026 server for IBM z/OS mainframes - with 24x7 support\r\nPuTTY client for Windows and Linux\r\nWinSCP client for Windows\r\nCyberDuck client for Mac\r\nOpenSSH server for Unix, Linux\r\nOverview of client alternatives\r\nOverview of server alternatives\r\nWindows SSH alternatives\r\nPrivX™ Privileged Access Management for multi-cloud\r\nRunning \u0026 configuring SSH\r\nhttps://www.ssh.com/ssh\r\nPage 2 of 4\n\nThis section contains links topics around using, configuring, and administering SSH.\r\nCommand line options\r\nTectia SSH manuals\r\nsshd - The SSH server on Unix/Linux\r\nsshd_config - Server configuration file on Unix/Linux\r\nssh_config - Client configuration file on Unix/Linux\r\nSSH port, and how it got that number\r\nSecurity of SSH and attacks against it\r\nThe SSH protocol is believed to be secure against cryptographic attacks on the network, provided keys and\r\ncredentials are properly managed. However, we do not recommend using diffie-hellman-group1-sha1 key\r\nexchange. It uses a 768 bit Diffie-Hellman group, which may be breakable by governments today. Larger groups\r\nare probably ok. Recent OpenSSH versions have disabled this group by default. See sshd_config for configuring\r\nwhat key exchanges to use.\r\nAnalysis of BothanSpy and Gyrfalcon - the presumed CIA hacking tools\r\nMan-in-the-middle attacks against SSH\r\nImperfect forward secrecy - How Diffie-Hellman fails in practice\r\nAutomate with SSH keys, but manage them\r\nSSH keys can be used to automate access to servers. They are commonly used in scripts, backup systems,\r\nconfiguration management tools, and by developers and sysadmins. They also provide single sign-on, allowing the\r\nhttps://www.ssh.com/ssh\r\nPage 3 of 4\n\nuser to move between his/her accounts without having to type a password every time. This works even across\r\norganizational boundaries, and is highly convenient.\r\nHowever, unmanaged SSH keys can become a major risk in larger organizations.\r\nWhat is an SSH key\r\nWhat SSH life cycle management means\r\nUniversal SSH Key Manager\r\nssh-keygen - Create keys\r\nssh-copy-id - Provision access on servers\r\nauthorized_keys - Authorized keys file format\r\nThe PrivX On-Demand Access Manager can be used as an alternative for SSH keys, eliminating the need for\r\npermanent keys and passwords on servers entirely.\r\nHistory of the SSH protocol\r\nThe Secure Shell protocol was originally developed by Tatu Ylonen in 1995 in response to a hacking incident in\r\nthe Finnish university network. A password sniffer had been installed on a server connected directly to the\r\nbackbone, and when it was discovered, it had thousands of usernames and passwords in its database, including\r\nseveral from Ylonen's company.\r\nThat incident triggered Ylonen to study cryptography and develop a solution he could use himself for remote login\r\nover the Internet safely. His friends proposed additional features, and three months later, in July 1995, Ylonen\r\npublished the first version as open source. It became OpenSSH. Later he took the protocol for standardization at\r\nthe IETF and designed the SSH File Transfer Protocol (SFTP). He founded SSH Communications Security Corp\r\nin December 1995 to provide commercial support for the protocol.\r\nYlonen still works on topics related to Secure Shell, particularly around key management, as well as broader\r\ncybersecurity topics.\r\nToday, the protocol is used for managing more than half of world’s web servers and practically every Unix or\r\nLinux computer, on-premise and in the cloud. Information security specialists and system administrators use it to\r\nconfigure, manage, maintain, and operate most firewalls, routers, switches, and servers in the millions of mission-critical networks and environments of our digital world. It is also embedded inside many file transfer and systems\r\nmanagement solutions.\r\nThe new protocol replaced several legacy tools and protocols, including telnet, ftp, FTP/S, rlogin, rsh, and rcp.\r\nSource: https://www.ssh.com/ssh\r\nhttps://www.ssh.com/ssh\r\nPage 4 of 4",
	"extraction_quality": 1,
	"language": "EN",
	"sources": [
		"MITRE"
	],
	"references": [
		"https://www.ssh.com/ssh"
	],
	"report_names": [
		"ssh"
	],
	"threat_actors": [],
	"ts_created_at": 1775434150,
	"ts_updated_at": 1775791230,
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