Enabling options at Control Panel > Terminal & SNMP > Terminal allows your Synology NAS to support Telnet and SSH command-line interface services. You can also change the security level of the SSH encryption algorithm.

To enable Telnet/SSH service:

  1. Check the box next to the desired protocol (SSH or Telnet).
  2. Click Apply.

To change SSH service port:

  1. In Port, enter a new port number.
  2. Click Apply.

A variety of encryption algorithms with different security levels are used in securing SSH connections. You can decide which algorithms are used to best meet your needs.

To change the SSH encryption algorithm security level:

  1. Click Advanced Settings.
  2. Select a security level for the encryption algorithms. If you want to specify exactly which algorithms can be used, select Customize to choose from three groups: Cipher, KEX (Key Exchange), and MAC (Message Authentication Code).
  3. Click Apply.

Some models support hardware acceleration for certain encryption algorithms. You can check the option Only use hardware accelerated ciphers to improve the transfer speeds of SSH-related services, including encrypted Network Backup and SFTP services. In the advanced page, algorithms capable of using hardware acceleration are shown in red.