Why will it happen?

The too several authentication failures error typically happens once somebody making an attempt to login into your server via VNC with the incorrect login credentials. it'd be brute forcing mistreatment some quite bots or scripts. Here i'm providing the thanks to get onto back to figure.

How to come back to VNC access?

1. Login to the server via SSH.
2. Get PID of the current VNC session by using 'pgrep' command:

   # pgrep vnc
   6981

3. Kill the PID you got as the result of 'pgrep':

   # kill 6981

4. Restart a new VNC session:

   #vncserver

VNC Too Several Authentication Failures Error Server How to Resolved

In order to form positive that the problem isn't happening once more, we are able to permit access to the VNC port for the specified public IPs solely and interference all others on the firewall. however it wants a static IP otherwise it'll be modified on every occasion and can cause a lot of access problems. Here i'm providing the steps to whitelist the specified IPs and interference the opposite ranges exploitation IPTABLES

1. You can list the currently active firewall rules:

   # iptables -L

2. You can add a rule to allow your IP on a specific port:

   # iptables -I INPUT -p tcp -s  your-ip --dport 5901 -j ACCEPT

   
   Here you need to replace the field 'your-ip' with the IP address and change the VNC port as per your VNC setup.
3. Once allowed all of your IPs/ranges, we need to block all others:

   # iptables -A INPUT -p tcp -s 0.0.0.0/0 --dport 5901 -j DROP

   ---
   Make sure that you have allowed all required IPs before activating the above rule, otherwise, the access will be gone. That's it.