Modern secure SSH daemon config

sshd_config

# Modern secure (OpenSSH Server 7+) SSHd config by HacKan
# Refer to the manual for more info: https://www.freebsd.org/cgi/man.cgi?sshd_config(5)

# Server fingerprint
# Regenerate with: ssh-keygen -o -f /etc/ssh/ssh_host_rsa_key -N '' -t rsa -b 4096
HostKey /etc/ssh/ssh_host_rsa_key
# Regerate with: ssh-keygen -o -f /etc/ssh/ssh_host_ed25519_key -N '' -t ed25519
HostKey /etc/ssh/ssh_host_ed25519_key

# Log for audit, even users' key fingerprint
LogLevel VERBOSE

# Ciphers and keying
RekeyLimit 1G 1H
KexAlgorithms [email protected],diffie-hellman-group18-sha512,diffie-hellman-group16-sha512,diffie-hellman-group14-sha256
Ciphers [email protected],[email protected],[email protected],aes256-ctr,aes192-ctr
MACs [email protected],[email protected],[email protected]

# Limit sessions and its duration
MaxAuthTries 2
MaxSessions 5
ClientAliveInterval 30
ClientAliveCountMax 6
TCPKeepAlive no

UsePAM yes
PasswordAuthentication no
ChallengeResponseAuthentication no
PubkeyAuthentication yes

# You can request for several auth methods to grant access, one next to the other
#AuthenticationMethods publickey

# Enable AllowAgentForwarding if you need to jump through this host
AllowAgentForwarding no
AllowTcpForwarding no
X11Forwarding no
PrintMotd no
Compression no

# Only if you really need it:
#AcceptEnv LANG LC_*

# Enable sftp only if needed
# For Arch Linux and Debian 10+
#Subsystem       sftp    /usr/lib/ssh/sftp-server
# For Debian/Ubuntu
#Subsystem sftp /usr/lib/openssh/sftp-server -f AUTHPRIV -l INFO

# Set authorized keys file
# Prefer using an admin-controlled environment
#AuthorizedKeysFile      /etc/ssh/authorized_keys/%u
AuthorizedKeysFile      .ssh/authorized_keys

# Restrict SSH usage per user or per group (uncomment any, or all, to use)
#AllowUsers	<your username>
#AllowGroups ssh-user

After applying any sshd config, ALWAYS check with a NEW connection that you still have access to the server. NEVER close the current connection without verifying that the config is correct!