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Posted to user@guacamole.apache.org by "Devine, Harry (FAA) via user" <us...@guacamole.apache.org> on 2026/02/03 15:30:52 UTC
Issue with RDP
We have some users that are using a Windows 2022 server in their environment, and with version 1.5.5, they always get the following error message:
RDP Server closed/refused connection: Server refused connection (wrong security type?)
In looking their connections, it looks like they are using RDP on port 3389 and the security mode is "RDP encryption". One server is Windows 2016 and they can get in, and the other is Windows 2022 and they get the error noted above.
Any help would be appreciated.
Thanks,
Harry
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Harry Devine
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RE: Issue with RDP
Posted by "Devine, Harry (FAA) via user" <us...@guacamole.apache.org>.
We don’t control the server but the admin hasn’t added their user used in the Guacamole connection to the Remote Desktop Users group yet. We’re waiting for him to do that an report back. It looks like he changed the Security Mode back to RDP encryption, so once he does the user update, we’ll make sure that we set the mode to Any and try it out.
Thanks,
Harry
From: Nick Couchman <vn...@apache.org>
Sent: Tuesday, February 3, 2026 2:47 PM
To: user@guacamole.apache.org
Cc: Devine, Harry (FAA) <ha...@faa.gov>
Subject: Re: Issue with RDP
CAUTION: This email originated from outside of the Federal Aviation Administration (FAA). Do not click on links or open attachments unless you recognize the sender and know the content is safe.
On Tue, Feb 3, 2026 at 12:52 PM Devine, Harry (FAA) via user <us...@guacamole.apache.org>> wrote:
Nick implied enabling NLA based on the wording. You’re saying to disable it?
I would not disable NLA on Windows, I would change the security setting for the Guacamole connection to connect with NLA instead of RDP Encryption, or, at the very least, negotiate.
-Nick
Re: Issue with RDP
Posted by Nick Couchman <vn...@apache.org>.
On Tue, Feb 3, 2026 at 12:52 PM Devine, Harry (FAA) via user <
user@guacamole.apache.org> wrote:
> Nick implied enabling NLA based on the wording. You’re saying to disable
> it?
>
>
>
I would not disable NLA on Windows, I would change the security setting for
the Guacamole connection to connect with NLA instead of RDP Encryption, or,
at the very least, negotiate.
-Nick
>
RE: Issue with RDP
Posted by "Devine, Harry (FAA) via user" <us...@guacamole.apache.org>.
Nick implied enabling NLA based on the wording. You’re saying to disable it?
Thanks,
Harry
From: Sean Hulbert <sh...@securitycentric.net>
Sent: Tuesday, February 3, 2026 11:53 AM
To: user@guacamole.apache.org
Subject: Re: Issue with RDP
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Nick is correct, you will need to disable NLA on Windows server 2022, also if youa re not logging in as Administrator you will need to add the user account to the Remote desktop group permissions.
Thank You
Sean Hulbert
Security Centric Inc.
A Cybersecurity Virtualization Enablement Company
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On 2/3/2026 7:52 AM, Nick Couchman wrote:
On Tue, Feb 3, 2026 at 10:32 AM Devine, Harry (FAA) via user <us...@guacamole.apache.org>> wrote:
We have some users that are using a Windows 2022 server in their environment, and with version 1.5.5, they always get the following error message:
RDP Server closed/refused connection: Server refused connection (wrong security type?)
In looking their connections, it looks like they are using RDP on port 3389 and the security mode is “RDP encryption”. One server is Windows 2016 and they can get in, and the other is Windows 2022 and they get the error noted above.
I'm shocked RDP Encryption works for 2016, and certainly would not expect it to work for 2022. I'd suggest trying NLA.
-Nick
Re: Issue with RDP
Posted by Sean Hulbert <sh...@securitycentric.net>.
Nick is correct, you will need to disable NLA on Windows server 2022,
also if youa re not logging in as Administrator you will need to add the
user account to the Remote desktop group permissions.
*Thank You*
Sean Hulbert
*Security Centric Inc.*
A Cybersecurity Virtualization Enablement Company
/StormCloud Gov, Protected CUI Environment!/
Industry's most secure CMMC/iTAR virtual desktops!
CMMC L2
*/FedRAMP MIL4 Ready FR2409250874/*
System Award Management
*CAGE: 8AUV4*
*SAM ID: UMJLJ8A7BMT3*
AFCEA San Francisco Chapter President
If you have heard of a hacker by name, he/she has failed, fear the
hacker you haven’t heard of!
CONFIDENTIALITY NOTICE: This communication with its contents may contain
confidential and/or legally privileged information. It is solely for the
use of the intended recipient(s). Unauthorized interception, review, use
or disclosure is prohibited and may violate applicable laws including
the Electronic Communications Privacy Act. If you are not the intended
recipient, please contact the sender and destroy all copies of the
communication. Content within this email communication is not legally
binding as a contract and no promises are guaranteed unless in a formal
contract outside this email communication.
igitur qui desiderat pacem, praeparet bellum!!!
Epitoma Rei Militaris
On 2/3/2026 7:52 AM, Nick Couchman wrote:
>
> On Tue, Feb 3, 2026 at 10:32 AM Devine, Harry (FAA) via user
> <us...@guacamole.apache.org> wrote:
>
> We have some users that are using a Windows 2022 server in their
> environment, and with version 1.5.5, they always get the following
> error message:
>
> RDP Server closed/refused connection: Server refused connection
> (wrong security type?)
>
> In looking their connections, it looks like they are using RDP on
> port 3389 and the security mode is “RDP encryption”. One server
> is Windows 2016 and they can get in, and the other is Windows 2022
> and they get the error noted above.
>
>
> I'm shocked RDP Encryption works for 2016, and certainly would not
> expect it to work for 2022. I'd suggest trying NLA.
>
> -Nick
>
Re: Issue with RDP
Posted by Nick Couchman <vn...@apache.org>.
On Tue, Feb 3, 2026 at 10:32 AM Devine, Harry (FAA) via user <
user@guacamole.apache.org> wrote:
> We have some users that are using a Windows 2022 server in their
> environment, and with version 1.5.5, they always get the following error
> message:
>
>
>
> RDP Server closed/refused connection: Server refused connection (wrong
> security type?)
>
>
>
> In looking their connections, it looks like they are using RDP on port
> 3389 and the security mode is “RDP encryption”. One server is Windows 2016
> and they can get in, and the other is Windows 2022 and they get the error
> noted above.
>
>
>
I'm shocked RDP Encryption works for 2016, and certainly would not expect
it to work for 2022. I'd suggest trying NLA.
-Nick
>