vCenter server filebased backups are failing for the SFTP protocol.

Products

• VMware vCenter Server

Issue/Introduction

Precisely the backups are failing for the SFTP and works for the other protocol. The backups are failing at 0% as soon as we start the backup.

Environment

vCenter Server Appliance  7.x 

vCenter Server Appliance 8.x

Cause

The SFTP backups is configured to  offer only the key based authentication, hence vCenter keeps trying the authentication and it fails eventually in the initial communication as the authentication is never established. 

 

 

Resolution

• The SFTP backup server config file has to be changed, To offer only the password based authentication and not key based.
• This configuration file is for Linux based SFTP server.
• If that's the only option we can manually configure the key based authentication on the vCenter server. 

Additional Information

• SSH into the SFTP server and check the configuration file of the SFTP server.
• Path to check the configuration file on the SFTP server. 
  • cat /etc/ssh/sshd_config
  • set the PasswordAuthentication Yes and PubkeyAuthentication no and comment out the line.
    • PubkeyAuthentication no
    • PasswordAuthentication yes

#PermitRootLogin prohibit-password
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

PubkeyAuthentication no

# The default is to check both .ssh/authorized_keys and .ssh/authorized_keys2
# but this is overridden so installations will only check .ssh/authorized_keys
AuthorizedKeysFile .ssh/authorized_keys

#AuthorizedPrincipalsFile none

# For this to work you will also need host keys in %programData%/ssh/ssh_known_hosts
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes

# To disable tunneled clear text passwords, change to no here!
PasswordAuthentication yes
#PermitEmptyPasswords no

# GSSAPI options
#GSSAPIAuthentication no

#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
#PermitTTY yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#PermitUserEnvironment no
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS no
#PidFile /var/run/sshd.pid