A cipher is an algorithm for performing encryption or decryption, a series of well-defined steps that can be followed as a procedure.
In Backup4all, ciphers are used for SFTP locations (source or destination) in case your SFTP server is installed on a Linux/Unix server.
Sometimes Backup4all gives you
Unsupported cipher Connection lost error when it tries to connect to a Linux/Unix server. That means the ciphers needed by Backup4all are not enabled on that Linux/Unix server.This article explains how to enable the necessarily ciphers on Linux.
Please follow these steps:
1. Download and install Putty from: https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html
2. Login with Putty as root user
3. List ciphers enabled on your server:
ssh -Q ciphers
4. Enable the necessarily ciphers in sshd_config file:
nano /etc/ssh/sshd_config
# or: mcedit /etc/ssh/sshd_config
5. Add these lines at the end of the sshd_config file:
Ciphers +aes256-ctr
MACs +hmac-sha1
HostKeyAlgorithms +ssh-rsa
KexAlgorithms +diffie-hellman-group14-sha1
PubkeyAcceptedKeyTypes +ssh-rsa
6. Restart sshd service by running:
service sshd restart
Then try again to run the backup.