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RE: "Too many security failures" with RealVNC 4.1

fbkj — Thu, 03 Apr 2008 00:43:22 GMT

I had the same problem. It went away over night. But I suspect the reason must be ....... ?? :

Here's my setup and what happened :

I have multiple instances of VNC clients running on a MACintosh (Eggplant from Redstone software).

The MACintosh has a network connection to a RedHat linux machine.

The RedHat linux is running one instance of VNCserver, never ever had any problems with it.

The RedHat linux is configured with IP port forwarding, to forward VNC (:59nn) traffic to several windows XP PCs (:5900) on the other network connected to the RedHat linux box. And each PC has a ROUTE ADD entry to tell it to reply via the RedHat linux box.

That way, the VNCclient instances on the MACintosh can access the VNCserver on each of the windows XP PCs via the RedHat linux IP by using different port numbers (:59nn).

This has been working just fine for about a month now.

But yesterday,... when attempting to connect to the VNCserver on one of the windows XP PCs for the first time in many days, I suddenly got this error message "Too many security failures". ....... I restarted the MAC and the RedHat and entered the ipforwarding on the RedHat over again, but it made no difference.

Then I attempted to run a VNCclient directly from the RedHat machine to the windows XP machine, and voila, that was working just fine. .... Back to the MACintosh again, but noooop,... still the same error message. (ping worked fine, nothing wrong with the connections).

Then I remembered that I had several windows XP PCs set up (but not used before),... and yup,..... they were working just fine. .... But the ones I had been using many days ago,... noooop.

Then I left for the day, and came back today.

And suddenly everything was working fine !-) ,.........

I realy don't have a clue as to why ?,.......

But my current logic is asking : could it be it was related to the IP address the VNC server was replying to, and that a timeout cured it ?

I do not know if my Eggplant VNC client software make any pollings towards the connections not in use. But I've never had any problems with the one I has been using almost every day.

I'm writing this in the hope that some VNC people maybe read it, and make sense out of it, and solve it in a future version.

RE: "Too many security failures" with RealVNC 4.1

sousou — Fri, 03 Jun 2005 00:53:12 GMT

I often see the "Too many security failures" message, and wait long time for login. It's terrible. So I decide to change it.

First i want to disable the waiting time. It is simple ,but too dangerous. Then i change to disable the waiting time double effect.

I am using the realvnc 4.1.6

Modify method:

1.Edit the "winvnc4.exe" with HEX editor

2.Search "d1e18948"

3.Change it to "90908948"

After the modify, the waiting time is always no more than 10 second.

RE: "Too many security failures" with RealVNC 4.1

Support (s-code) — Mon, 09 May 2005 18:03:19 GMT

Martha,
to fix the problem you should enable Native VNC authentication on a VNC server side. At the moment VNC Manager doesn't support RealVNC 4 Enterprise Edition authentication. But this feature should be supported in future, we are in talks with RealVNC guys and hopefully they will license us a source code for tier RealVNC Ent. Ed. software.

As for file transfers. TightVNC 1.3 file transfer has been implemented long time ago, and next build of VNC Manager will included support for UltraVNC file transfers. The build will be released within next 48 hours.

RE: "Too many security failures" with RealVNC 4.1

Martha Stewart — Mon, 09 May 2005 16:40:00 GMT

Any luck with this problem at all? I also have the same problem.

The error message it gives me is "No supported security type for 3.3 client"

And on the side note i was wondering what is available in the way of file transfers..?

Thanks for your time,

Martha

RE: "Too many security failures" with RealVNC 4.1

Bob Hartung — Wed, 23 Mar 2005 07:42:54 GMT

No, the units I installed RealVNC 4.1 on are only members of one group in VNC Manager. I also checked the Application Event Log on each of the systems and the error associated with VNC is "Connections: Blacklisted: 172.16.3.50". The IP address is of my PC running VNC Manager.

RE: "Too many security failures" with RealVNC 4.1

Support (s-code) — Wed, 23 Mar 2005 06:25:02 GMT

Bob,
I have an idea what might cause this behavior. In case if you have a server with the same IP added to a different folders, when during status update the server will be updated several times. Hence VNC Manager, will establish several connections to the VNC server within short time interval. What might cause security protection mechanism to trigger.

Let me know if that's so.

RE: "Too many security failures" with RealVNC 4.1

Support (s-code) — Tue, 22 Mar 2005 21:23:03 GMT

Bob,
could you please send config.xml and vnc_servers.xml to support@s-code.com ? The files are located at:
%USERPROFILE%\Application Data\Smart Code\VNC\Manager

PS: I need the files from the PC, on which you able to reproduce the problem.

RE: "Too many security failures" with RealVNC 4.1

Bob Hartung — Tue, 22 Mar 2005 21:02:31 GMT

Well, the "too many security failures" finally started on my original Win2000 server. I installed v4.1 on a Windows XP Pro PC and another Win2000 server and the problem appeared on them as well. Prior to this, all of them had v3.3.7 on them with no problems.

RE: "Too many security failures" with RealVNC 4.1

Bob Hartung — Tue, 22 Mar 2005 13:45:02 GMT

For testing purposes, I un-installed RealVNC v4.0 and re-installed v4.1 on the server having the problem. I then removed this server from VNC Manager and left everything connected overnight. In the morning, I was able to log into the server directly through RealVNC.

Now here's a strange development. I added the server back into VNC Manager with updates still happening every 15 minutes. I have been running that for about 6 hours now and no "security failures". I plan to install RealVNC 4.1 on a couple other systems and see how they work.

RE: "Too many security failures" with RealVNC 4.1

Support (s-code) — Mon, 21 Mar 2005 18:42:07 GMT

Bob,
yes this could be caused by Status updates feature. Because when it checks for a VNC server status, it establishes a connection to it. So from the server point of view, it looks like a connection attempt, which was terminated before VNC session has been established.
We will increase default status update interval, and put an information tip on a page with settings.

RE: "Too many security failures" with RealVNC 4.1

AdamMoore — Mon, 21 Mar 2005 16:12:37 GMT

Have you tried unchecking it to see if there is a difference?

"Too many security failures" with RealVNC 4.1

Bob Hartung — Mon, 21 Mar 2005 12:36:29 GMT

I've downloaded RealVNC v 4.1 Free Ed. and installed it on a Win2000(sp5) server to test it. Initially everything worked fine but then I started getting the error message "Too many sercurity failures. Do you wish to attempt to reconnect to 172.16.1.20? Yes/No". I found that it never works to answer yes, regardless of how long you wait for the security block to time-out. The only thing that does work is killing the VNC service and then restarting it.

I finally removed v4.1 and re-installed v4.0 and the problem stopped entirely.

The reason I'm posting this problem to this forum is that I am using VNC Manager v2.5.73 and I have VNC set to check for server status every 15 minutes. I'm also using VNC authentication for access. Is there a chance that VNC Manager's status checking is somehow triggering RealVNC 4.1's tighter security?

For reference, here's a reply regarding the problem when I posted a question regarding this to the RealVNC discussion group. In particular, the last paragraph suggesting non-authenticated communication between my PC and the targer server.

Bob,

"Too many security failures" indicates that the IP address from which you
are connecting has been making lots of connections to the VNC Server that
didn't end up being successfully authenticated.

This is a security feature designed to prevent dictionary attacks on
servers, by preventing machines from making large numbers of connections to
a server over a short period of time.

The message is triggered by 5 failed authentication attempts, at which point
a 10 second lockout is applied before the next attempt is permitted. The
next failed attempt causes the timeout to be doubled.

Given that (I assume) you are seeing this message in spite of supplying
correct credentials each time you try to log in, and that once you see the
message you never again get the chance to enter a password, it sounds like
something is connecting to the server from the same IP address as your
viewer machine and is not authenticating, hence causing the failures.

VNC 4.0 was less secure in this respect, by default, hence the different
behaviour.

Cheers,

Wez @ RealVNC Ltd.