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I am trying to use VNC to vnc4server from the Remmina client via an ssh tunnel. I establish the ssh tunnel with ssh -L 5901:127.0.0.1:5901 user@remoteIp I have had successful VNC sessions to this server in the past. However I am now getting an error.

What is the cause of this Remmina error message.

VNC connection failed: Too many security failures

Does this mean somebody is trying to intrude (hack into) my server?

How would I investigate this? I have a login session which I can use to investigate this because the command to setup the ssh tunnel gives me a shell prompt.

H2ONaCl
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  • For me I had a VNC connection to a remote Ubuntu machine from a local virtual machine Ubuntu guest, and I performed a "save state" on the VM so the next time I tried to login I got that error. Thus I was added to the VNC blacklist. Of course you need to investigate why you are getting that error, but if you are sure that it is not a security vulnerability then to re-allow VNC connections and clear the blacklist simply wait a while or stop and restart your vnc server. For details please see https://help.realvnc.com/hc/en-us/articles/360003563111-Too-Many-Security-Failures – user8128167 Dec 20 '19 at 23:21

1 Answers1

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The information at this link suggests to me that it was an attempt at intrusion. To succeed in establishing a VNC session a legitimate user must wait. In practice waiting a few minutes is necessary before a successful VNC session is allowed once again. There is no need to re-establish the ssh tunnel.

H2ONaCl
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  • So intruders were able to ssh into the server but failed to log into the VNC server? Sounds like you have more to worry about than just getting logged on. – symcbean Jan 27 '18 at 22:53
  • @symcbean, I edited to correct the record. – H2ONaCl Jan 29 '18 at 20:02