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5.2 SSH Connection Failure

Typical Symptoms​

Error messages appear when adding a device in Device Management or executing SSH commands:

  • ssh: connect to host X.X.X.X port 22: Connection timed out
  • Permission denied (publickey,password)
  • Host key verification failed
  • Connection refused

Quick Diagnosis​

Perform the following two-step diagnosis in order:

  1. ping <Device IP>:
  2. ssh root@<Device IP>:
    • Permission denied → Incorrect username or password; default credentials for official RDK images are root / root
    • timed out → The SSH daemon (sshd) is not running on the device
    • Host key verification failed → The device's OS was reflashed; clear the old host key as described below under "Clear Old Host Keys"

Troubleshooting Checklist​

  1. Network Reachability: Run ping <Device IP>. If packet loss exceeds 5%, proceed directly to 5.7.
  2. SSH Service Running on Device: Log into the device via serial console or another method and run:
    systemctl status ssh && netstat -tlnp | grep :22
  3. Correct Credentials: Official RDK images use root/root by default. When using custom credentials, ensure "Custom Credentials" is checked in Studio.
  4. Firewall Rules: On Windows, configure third-party firewalls to allow outbound traffic for ssh.exe and inbound traffic on port 22.
  5. Host Key Changed: After reflashing the device image, its host key changes. On your PC, run ssh-keygen -R <Device IP> to remove the old key.

Common Default IPs at a Glance​

Connection MethodDefault IPSubnet
Type-C Flash Connection192.168.128.10192.168.128.0/24 (PC side: .100)
Ethernet Direct (X5)192.168.127.10192.168.127.0/24
WiFi / DHCPAssigned by routerScan with nmap -sn 192.168.1.0/24, or check your router’s admin interface

Permanent Solutions​

  • Enable Auto Reconnect for frequently used devices.
  • Use SSH keys instead of passwords: ssh-copy-id root@<IP>
  • Configure a static IP on production devices (modify /etc/dhcpcd.conf or use nmcli)
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