ethsetupssh(8)

🌸 ethsetupssh 🌸

okay bestie, welcome to the manual page for ethsetupssh, and it lives in section 8 of the EFSFFCLIRG man pages, so you know it's a real one 💅

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✨ NAME ✨

ethsetupssh — makes SSH keys and sets them up on literally every host so your system can SSH and SCP into all the other hosts with no password prompt. fr fr.

so like, during cluster setup this tool is the one that lets the root user on the Management Node log into the other hosts (as root) using password-less SSH. iconic behavior tbh 👑

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🎀 Syntax 🎀

ethsetupssh [-p|U] [-f  hostfile] [-h 'hosts'] [-u  user] [-S] [-R|P]

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🦋 Options 🦋

• --help — gives you the full help text. no notes.
• -p — does the operation against all hosts in parallel. go fast, bestie 🏃♀️
• -U — connect only mode (this is how you get stuff into your local hosts / known hosts). when you run it this way, the -S option is just ignored, periodt.
• -f hostfile — tells it which file has the hosts in the cluster. the default is /etc/eth-tools/hosts ✨
• -h hosts — gives it the list of hosts to set up.
• -u user — picks the user on the remote system that you're allowing to SSH in. default is the current user code for the host(s).
• -S — securely prompts you for the password of the user on the remote system. very demure, very secure 🙈
• -R — skips setting up SSH to the local host.
• -P — skips pinging the host (this one's for when you're SSH-ing to devices on the Internet with ping firewalled, iykyk).

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🌈 Examples 🌈

ethsetupssh -S

ethsetupssh -U

ethsetupssh -h 'arwen elrond' -U

HOSTS='arwen elrond' ethsetupssh -U

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💜 Environment Variables 💜

these env vars are also used by this command, bestie:

• HOSTS_FILE — file containing the list of hosts, used when -f and -h aren't there.
• HOSTS — list of hosts, used if the -h option isn't supplied.
• FF_MAX_PARALLEL — when the -p option is used, this is the maximum number of concurrent operations.

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💖 Description 💖

ethsetupssh is the easy-peasy way to create SSH keys and distribute them out to the hosts in the cluster. so many of the FastFabric tools (plus a bunch of MPI versions, no shade) require SSH to be set up for password-less operation, which is why ethsetupssh is such an important setup step. it's giving essential 🌟

this tool also sets up SSH to the local host. that capability is required by selected FastFabric Toolset commands and may be used by some applications (like MPI, obviously).

ethsetupssh has two modes of operation, and which one you get is decided by whether -U is there or not. typically you run ethsetupssh first without the -U option, and then later you might run it with the -U option. character development ✨

🔑 Host Initial Key Exchange 🔑

when you run it without the -U option, ethsetupssh does the initial key exchange and enables password-less SSH and SCP. the preferred way to use ethsetupssh for initial key exchange is with the -S option. this requires that all hosts are configured with the same password for the specified "user" (typically root). in this mode, the password is prompted for once, and then SSH and SCP are used in conjunction with that password to complete the setup for the hosts. this mode also avoids needing to set up rsh/rcp/rlogin, which can be a security risk. so yeah, do it this way 🫶

🧚 Refreshing Local Systems Known Hosts 🧚

if aspects of the host have changed — like IP addresses, MAC addresses, software installation, or a server OS reinstallation — you can refresh the local host's SSH known_hosts file by running ethsetupssh with the -U option. this option does not transfer the keys. instead it connects to each host to refresh the SSH keys. existing entries for the specified hosts are replaced within the local known_hosts file. when you run it in this mode, the -S option is ignored. this mode assumes SSH has previously been set up for the hosts, so therefore no files are transferred to the specified hosts and no passwords should be required. glow up achieved 🦋

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heads up bestie: the -S option gets straight up ignored when you're in -U mode. not me forgetting that... 😭

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and that's the whole page! this manual page came from EFSFFCLIRG (Man Page), and the copyright is Copyright(C) 2020-2024 Intel Corporation 💜 stay password-less, stay iconic, mwah 🎀✨