Error acessing Plesk-SSH-Terminal: Connection Broken

Symptoms

• Unable to access the Plesk SSH Terminal:

  PLESK_ERROR: Connection Broken

• Error in logs /var/log/syslog:
  

  CONFIG_TEXT: Jan 19 14:36:09 happy-jones plesk-ssh-terminal.x86-64[154167]: 2025/01/19 14:36:09 remote=203.0.113.2 WebSocket new connection via unix @
  Jan 19 14:36:09 happy-jones plesk-ssh-terminal.x86-64[154167]: 2025/01/19 14:36:09 failed to read from shell: read /dev/ptmx: input/output error
  Jan 19 14:36:09 happy-jones plesk-ssh-terminal.x86-64[154167]: 2025/01/19 14:36:09 send SIGINT to shell process 159707

• Additional errors in logs /var/log/auth.log:
  

  CONFIG_TEXT: Jan 19 14:36:09 happy-jones sshd[159708]: Unable to negotiate with 127.0.0.1 port 51328: no matching host key type found. Their offer: ssh-ed25519-cert-v01@openssh.com,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,sk-ssh-ed25519-cert-v01@openssh.com,sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ssh-ed25519@openssh.com,sk-e

Cause

There are customizations in file /etc/ssh/sshd_config:

CONFIG_TEXT: TrustedUserCAKeys /etc/ssh/ca.pub
AuthorizedPrincipalsFile /etc/ssh/auth_principals/%u
CASignatureAlgorithms +ssh-rsa
HostKeyAlgorithms=ssh-rsa,ssh-rsa-cert-v01@openssh.com
PubkeyAcceptedAlgorithms=+ssh-rsa,ssh-rsa-cert-v01@openssh.com
KexAlgorithms +diffie-hellman-group14-sha1

Resolution

1. Log in to Plesk.

2. Connect to the Plesk server via SSH.

3. Comment the customizations
4. Execute command:

   # systemctl restart ssh.service