On Sat, May 23, 2026 at 7:09 PM Devine, Harry (FAA) <[email protected]>
wrote:
> When I run the TigerVNC client viewer from one of our VMs to my VNC
> server, I get prompted for the password. My connection DOES have the
> password in it (see attached screenshot, with the password hidden and the
> hostname blanked out for redaction), so that’s probably why. But that
> password in the Guac connection is the exact same password that is
> configured for the user at port 5902, and the one that I enter when the
> viewer prompts me.
>
>
>
> It seems that, for some reason, Guacamole just isn’t sending the password.
> And based on the tcpdump that my network admin looked over, with the Guac
> connection attempt, the VNC server sends back a hex value to, I believe,
> encrypt the connection password and send back to the server, but Guac seems
> to just send back that same hex value.
>
>
>
Yeah, this is really puzzling - I've tried my best to replicate the
environment that you have, and, if I put the password in the connection
settings, it works fine and connects immediately, and if I leave the
password blank, it prompts for it and works fine.
I did a pcap on my side, as well, and get the following:
==
Frame 8: Packet, 68 bytes on wire (544 bits), 68 bytes captured (544 bits)
Ethernet II, Src: ProxmoxServe_8f:6f:0d (bc:24:11:8f:6f:0d), Dst:
ProxmoxServe_a2:87:83 (bc:24:11:a2:87:83)
Internet Protocol Version 4, Src: 192.168.51.136, Dst: 192.168.50.1
Transmission Control Protocol, Src Port: 5901, Dst Port: 54024, Seq: 13,
Ack: 13, Len: 2
Virtual Network Computing
Number of security types: 1
Security type: VNC (2)
==
Frame 9: Packet, 67 bytes on wire (536 bits), 67 bytes captured (536 bits)
Ethernet II, Src: ProxmoxServe_a2:87:83 (bc:24:11:a2:87:83), Dst:
ProxmoxServe_8f:6f:0d (bc:24:11:8f:6f:0d)
Internet Protocol Version 4, Src: 192.168.50.1, Dst: 192.168.51.136
Transmission Control Protocol, Src Port: 54024, Dst Port: 5901, Seq: 13,
Ack: 15, Len: 1
Virtual Network Computing
Security type selected: VNC (2)
==
Frame 10: Packet, 82 bytes on wire (656 bits), 82 bytes captured (656 bits)
Ethernet II, Src: ProxmoxServe_8f:6f:0d (bc:24:11:8f:6f:0d), Dst:
ProxmoxServe_a2:87:83 (bc:24:11:a2:87:83)
Internet Protocol Version 4, Src: 192.168.51.136, Dst: 192.168.50.1
Transmission Control Protocol, Src Port: 5901, Dst Port: 54024, Seq: 15,
Ack: 14, Len: 16
Virtual Network Computing
Authentication challenge: f04a54958cd782731d48550c8e1c2aa9
==
Frame 11: Packet, 82 bytes on wire (656 bits), 82 bytes captured (656 bits)
Ethernet II, Src: ProxmoxServe_a2:87:83 (bc:24:11:a2:87:83), Dst:
ProxmoxServe_8f:6f:0d (bc:24:11:8f:6f:0d)
Internet Protocol Version 4, Src: 192.168.50.1, Dst: 192.168.51.136
Transmission Control Protocol, Src Port: 54024, Dst Port: 5901, Seq: 14,
Ack: 31, Len: 16
Virtual Network Computing
Authentication response: 69dac1a77bbba48f23b6aed80e25a044
==
Frame 12: Packet, 70 bytes on wire (560 bits), 70 bytes captured (560 bits)
Ethernet II, Src: ProxmoxServe_8f:6f:0d (bc:24:11:8f:6f:0d), Dst:
ProxmoxServe_a2:87:83 (bc:24:11:a2:87:83)
Internet Protocol Version 4, Src: 192.168.51.136, Dst: 192.168.50.1
Transmission Control Protocol, Src Port: 5901, Dst Port: 54024, Seq: 31,
Ack: 30, Len: 4
Virtual Network Computing
.... .... .... .... .... .... .... ...0 = Authentication result: OK
==
-Nick
