To resolve this issue, ensure to use the ciphers which are supported for SFTP backup in NSX 6.3.x through 6.3.4.
Supported ciphers:
Encryption: aes128-cbc, aes128-ctr, aes192-cbc, aes192-ctr, aes256-cbc, aes256-ctr
Message Authentication(mac): hmac-sha2-256
Key Exchanges: diffie-hellman-group-exchange-sha256
Compressions: none, zlib
To configure the sftp server CIPHER / MAC Algorithms:
- Edit the /etc/ssh/sshd_config file.
- sshd_config keywords Cipher and MACs need to be updated with the correct Cipher and MAC algorithms.
For example:
Ciphers aes128-cbc,aes128-ctr,aes192-cbc,aes192-ctr,aes256-cbc,aes256-ctr
MACs hmac-sha2-256