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Posted to user@guacamole.apache.org by kpham <kp...@fastmail.com> on 2017/11/13 17:47:43 UTC
Intermittent VNC connectivity to IP KVM
This is a weird issue.
I use Adderlink IP KVM which uses VNC protocol. When I connect to the IPKVM
from Guacamole v0.9.1.3, the connection drops every time something changes
significant on the client's monitor (Ex. Maximize a screen, close a
windows...etc). If I connect to the IPKVM and do nothing, the connection
stays on.
I have tried with multiple units and has the same issue. I checked syslog
and got this message everytime it happens
kernel: [20018.150998] traps: guacd[2185] trap divide error ip :
7f493214dbcd sp:7f4932d70b80 error:0 in
libvncclient.so.1.0.0[7f493213d0000+1e0000]
Do you think it's a bug in vncclient module? Any suggestion for me on how to
fix it ?
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Re: Intermittent VNC connectivity to IP KVM
Posted by kpham <kp...@fastmail.com>.
Hi Mike, thank you for your instruction. I attempted to report it to LibVNC
Github but it is difficult to point exactly where the issue is with them.
It's a bit confusing with logs from Guacamole about LibVNC :) . I will try
to write a better post to them.
On a follow up question, please help me (Just on high level, just need
directions, I can Google the rest), how do you "Installing the absolute
latest libvncclient (part of libvncserver), rebuilding guacamole-server" ?
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Re: Intermittent VNC connectivity to IP KVM
Posted by Mike Jumper <mi...@guac-dev.org>.
On Mon, Nov 13, 2017 at 9:47 AM, kpham <kp...@fastmail.com> wrote:
> ...
> kernel: [20018.150998] traps: guacd[2185] trap divide error ip :
> 7f493214dbcd sp:7f4932d70b80 error:0 in
> libvncclient.so.1.0.0[7f493213d0000+1e0000]
>
> Do you think it's a bug in vncclient module? Any suggestion for me on how
> to
> fix it ?
>
>
This does look like a bug in libvncclient, the library used by Guacamole's
VNC support to handle the VNC protocol. It's hard to tell exactly where
within the library this is happening, but the kernel is reporting here that
the library is attempting to divide by zero. My guess, given context, is
that the VNC server is sending an empty rectangle with one of the
dimensions being zero, and libvncclient is improperly handling this
condition.
I would recommend installing the absolute latest libvncclient (part of
libvncserver), rebuilding guacamole-server, and seeing if the problem is
resolved. If the bug remains, the next step would be to report it upstream:
https://github.com/LibVNC/libvncserver
- Mike
Re: Intermittent VNC connectivity to IP KVM
Posted by kpham <kp...@fastmail.com>.
I turned debug mode on, and it show less message when disconnect
Please see the image
<http://apache-guacamole-incubating-users.2363388.n4.nabble.com/file/t436/vnc-debug-2.png>
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Re: Intermittent VNC connectivity to IP KVM
Posted by Nick Couchman <vn...@apache.org>.
On Mon, Nov 13, 2017 at 12:47 PM, kpham <kp...@fastmail.com> wrote:
> This is a weird issue.
>
> I use Adderlink IP KVM which uses VNC protocol. When I connect to the IPKVM
> from Guacamole v0.9.1.3, the connection drops every time something changes
> significant on the client's monitor (Ex. Maximize a screen, close a
> windows...etc). If I connect to the IPKVM and do nothing, the connection
> stays on.
>
>
> I have tried with multiple units and has the same issue. I checked syslog
> and got this message everytime it happens
>
> kernel: [20018.150998] traps: guacd[2185] trap divide error ip :
> 7f493214dbcd sp:7f4932d70b80 error:0 in
> libvncclient.so.1.0.0[7f493213d0000+1e0000]
>
> Do you think it's a bug in vncclient module? Any suggestion for me on how
> to
> fix it ?
>
>
Can you put guacd into debug logging (-L debug) and see if you get any
additional output during the disconnects? guacd logs to /var/log/messages
(or wherever the default syslog destination is), so check those logs for
guacd entries.
-Nick
Re: Intermittent VNC connectivity to IP KVM
Posted by kpham <kp...@fastmail.com>.
<http://apache-guacamole-incubating-users.2363388.n4.nabble.com/file/t436/vnc-log1_LI.jpg>
Just want to show you the log
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