SSH kex_exchange_identification Connection Reset: Troubleshooting
SSH "kex_exchange_identification: Connection reset" means the server rejects before key exchange — usually MaxStartups limits, fail2ban, or firewall rules. Use ssh -vvv to diagnose.
The SSH error "kex_exchange_identification: read: Connection reset by peer" means the remote server is actively resetting the connection before the key exchange can begin. Common causes: - Server's `MaxStartups` limit reached (too many concurrent unauthenticated connections) - IP blocked by fail2ban or similar intrusion prevention system - Firewall or hosting platform rate limiting - SSH service overloaded or misconfigured - DenyHosts or AllowUsers/AllowGroups restrictions in sshd_config Troubleshooting steps: 1. Try connecting with verbose output: `ssh -vvv user@host` 2. Check if you can reach the port: `nc -zv host 22` 3. Try from a different IP/network (to rule out IP-based blocking) 4. Check server logs (`/var/log/auth.log` or `journalctl -u sshd`) 5. Verify sshd is running and listening: `ss -tlnp | grep 22` 6. Check fail2ban status: `fail2ban-client status sshd`