b2KIT

SSH Config Generator

Generate SSH client config files (~/.ssh/config) with host entries, jump proxies, and key specifications.

Tested tool guide Tested browser tools Checked August 16, 2026

What SSH Config Generator does, with a checked example

The tool turns each server you connect to - alias, hostname, user, port, key file, and any jump host - into a ready-to-paste block of ssh_config text for ~/.ssh/config, so you fill in fields instead of remembering keyword syntax. The format is pickier than it looks: keywords are case-insensitive and indentation is conventional, but the matching rules are exact. The thing people get wrong most often is ordering: ssh reads the file top to bottom and keeps the first value it finds for each option, so a broad Host * defaults block placed before your entries silently overrides them. Specific hosts first, defaults last.

Worked example

A concrete input and expected output from the current implementation.

Input

Fields: Alias web-prod; Hostname 203.0.113.42; User deploy; Port 2202; Key file ~/.ssh/web-prod; Jump host admin@bastion.example.com

Expected output

Host web-prod
    HostName 203.0.113.42
    User deploy
    Port 2202
    IdentityFile ~/.ssh/web-prod
    ProxyJump admin@bastion.example.com

Each field maps to one ssh_config keyword, so ssh web-prod now connects as deploy to 203.0.113.42 on port 2202 with the named key, routed through the bastion on its default port 22. The tilde in the IdentityFile stays literal in the file; ssh expands it when the connection runs.

How the result is produced

1

Host blocks and first-match ordering

Each entry becomes one Host block: the alias you enter is written after the Host keyword, and everything below it applies to connections matching that name. ssh scans the whole config top to bottom and applies the first value it finds for each option, so a later block only supplies options an earlier one left unset. Generated entries therefore behave predictably when placed before any catch-all defaults.

2

Keys and jump proxies

A key file becomes an IdentityFile line and a jump host becomes ProxyJump. Each hop authenticates independently: the bastion leg uses the user and keys named in the jump spec, the target leg uses the block's own User and IdentityFile. ProxyJump requires OpenSSH 7.3 or newer, covering any client from 2016 on. The text and your key paths stay in the browser; the output is plain text to save.

Good uses

  • Outfitting a new machine: you have a server inventory - aliases, users, ports, key paths - and want every ssh alias to work from day one instead of hand-typing blocks.
  • Reaching hosts behind a bastion: internal servers accept connections only through a jump host, and you need each entry to carry the right ProxyJump instead of typing -J flags before every command.
  • Rebuilding a config you no longer trust: re-enter each server's real values and get clean, consistent blocks whose lines all trace back to an input you chose, then retire the old file.

Limits and checks

  • Ordering in the final file is still your job. ssh applies the first value it finds for each option, so if a Host * defaults block sits above your generated entries, it silently overrides them for any option it sets. Place specific blocks first and catch-all defaults last, in whatever file you assemble.
  • Generation is not verification. Nothing here tests whether a hostname resolves, a port is open, or a key works; a wrong port or a typo surfaces only when ssh runs, as 'Connection refused', 'Host key verification failed', or 'Permission denied'. Treat the output as syntax, not proof.
  • Permissions still bite. ssh refuses to use a config file that is group- or world-writable, and skips private keys with loose permissions, so both ~/.ssh/config and the keys an IdentityFile names need chmod 600. The generator cannot fix that for you, and the error messages it leads to are easy to misread as a config problem.

Common questions

Where do I put the generated text, and do I have to restart anything?

Save it as ~/.ssh/config, or append the block to that file if it already has content. ssh reads the file on every connection, so changes take effect immediately, with no restart or reload. Keep the file at permissions 600, since ssh ignores configs that are group- or world-writable. To keep generated entries separate, save them to another file and connect with ssh -F /path/to/config alias.

I set an IdentityFile but ssh still used a different key, or asked for a password. Why?

By default, ssh offers keys loaded in your ssh-agent alongside the IdentityFile you listed, and the server chooses what it accepts, so your file is not the only key in play. Add IdentitiesOnly yes to the block and ssh will offer only the listed key files. If it still fails, check that the key path exists and the key's permissions are 600.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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