Error connecting to remote server using Teleport

System details:

Positron and OS details:

Positron Version: 2025.06.0 (user setup) build 167
Code - OSS Version: 1.100.0
Commit: e7e5d5590adc6bf7b760f837051cd2f57ea9e3dc
Date: 2025-05-29T21:05:45.949Z
Electron: 34.5.1
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Windows_NT x64 10.0.26100

Interpreter details:

N/A

Describe the issue:

When attempting to connect to a remote server, I get the following error:

[Trace  - 18:20:13.850] Identity keys:
C:\Users\me\.tsh\keys\teleport.<snip>\user@domain.com ssh-rsa SHA256:37+<snip>
[Trace  - 18:20:13.850] Spawning ProxyCommand: C:\Users\me\AppData\Local\programs\teleport-connect\resources\bin\tsh.exe proxy ssh --cluster=teleport-prod --proxy=teleport.<snip>:443 user@server:3022
[Error  - 18:20:14.318] Error resolving authority
Error: Handshake failed: no matching host key format

I can successfully ssh server from the terminal, and VSCode connects to the same host without issue on the same client.

The relevant parts of my .ssh/config are

CanonicalizeHostname yes
CanonicalDomains <snip>
User <snip>
HostkeyAlgorithms rsa-sha2-256-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com
PubkeyAcceptedAlgorithms rsa-sha2-256-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com
KexAlgorithms curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group14-sha256
ProxyCommand C:\Users\me\AppData\Local\programs\teleport-connect\resources\bin\tsh.exe proxy ssh --cluster=teleport-prod --proxy=teleport.<snip>:443 %r@%h:%p

And I can see from ssh -vvv server:

debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-c,kex-strict-c-v00@openssh.com
debug2: host key algorithms: ssh-rsa,ssh-ed25519,ecdsa-sha2-nistp256,rsa-sha2-512,rsa-sha2-256,rsa-sha2-512-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,ecdsa-sha2-nistp256-cert-v01@openssh.com
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group14-sha256,kex-strict-s-v00@openssh.com
debug2: host key algorithms: rsa-sha2-256-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com

So it is not obvious to me why the handshake is failing.

Steps to reproduce the issue:

1. Open Positron
2. Attempt to connect to remote server

Start by reproducing the Windows remote connection from the issue using the shown Teleport tsh.exe ProxyCommand, then compare it with the successful terminal and VS Code connections. Done means Positron can connect to the same server without the “no matching host key format” handshake error.