SSH guides

Diagnose SSH agent refused operation errors by checking loaded keys, socket ownership, keychain state, hardware tokens, permissions, and agent forwarding.

Resolve SSH key exchange negotiation failures by comparing client and server algorithms, updating legacy systems, and using narrow temporary compatibility settings.

Diagnose SSH kex_exchange_identification and connection closed errors by checking access controls, connection limits, bans, proxies, and sshd logs.

Diagnose SSH broken pipe errors and sessions that disconnect by checking idle timeouts, keepalives, network stability, bastions, and server logs.

Stop SSH from offering too many keys by identifying the effective identities, controlling ssh-agent, and configuring IdentitiesOnly safely.

Diagnose SSH timeouts by checking DNS, routing, firewalls, security groups, ports, proxies, and whether the server is reachable.

Find out why an SSH server refuses connections by checking the port, service status, firewall rules, bind address, and network path.

Resolve SSH host key verification failures safely by checking whether a server was rebuilt, its address changed, or the connection may be intercepted.

Diagnose SSH public key authentication failures by checking the offered key, file permissions, server configuration, and authentication logs.