infrastructure/ansible/roles/base/files/sshd_config

# TCP port to bind to
# Change to a high/odd port if this server is exposed to the internet directly
Port {{ ssh_port }}

AllowUsers {% if hostname_slug in pve_hosts %}{{ user }}@{{ pve_hosts.internal_cidr }}{% endif %} {% if hostname_slug in nebula.clients %}{{ user }}@{{ nebula.cidr }}{% endif %} {{ ssh_extra_allowed_users }}

# Bind to all interfaces (change to specific interface if needed)
ListenAddress 0.0.0.0

# Force SSHv2 Protocol
Protocol 2

HostKey /etc/ssh/ssh_host_ed25519_key

# Public key authentication + Password authentication
# Two-Factor Authentication in OpenSSH v6.2+
PubkeyAuthentication yes
AuthenticationMethods publickey

# Disable root SSH access
PermitRootLogin no

# Client timeout
ClientAliveInterval 60
ClientAliveCountMax 100

# Compression (only after authentication)
Compression delayed

# Logging
SyslogFacility AUTH
LogLevel INFO

# Authentication must happen within 30 seconds
LoginGraceTime 30

PermitEmptyPasswords no

# Check user folder permissions before allowing access
StrictModes yes

# Message Authentication Code (Hash, only SHA2-512)
# SHA-256 included for compat with PuTTY-WinCrypt clients
MACs hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,umac-128-etm@openssh.com

# Ciphers (only secure AES-256)
Ciphers aes256-ctr,aes128-gcm@openssh.com,aes128-ctr,aes192-ctr,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com

# Key Exchange algorithms (Elliptic Curve Diffie-Hellman)
# DH-SHA-256 included for compat with PuTTY-WinCrypt clients
KexAlgorithms diffie-hellman-group18-sha512,curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512

# Don't read the user's ~/.rhosts and ~/.shosts files
IgnoreRhosts yes

# Disable unused authentication schemes
HostbasedAuthentication no
ChallengeResponseAuthentication no
KerberosAuthentication no
GSSAPIAuthentication no
UsePAM no

# X11 support
X11Forwarding no

# Don't show Message of the Day
PrintMotd yes

# TCPKeepAlive (non-tunneled, disabled)
TCPKeepAlive no

# Allow client to pass locale environment variables
AcceptEnv LANG LC_*

Subsystem sftp internal-sftp