Add option for SSH routing through TOR for security reasons

[hitchhooker]

Add hardened SSH ruling as well as opening connection only through tor.

[hitchhooker]

#	$OpenBSD: sshd_config,v 1.104 2021/07/02 05:11:21 dtucker Exp $

# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.

# This sshd was compiled with PATH=/usr/local/sbin:/usr/local/bin:/usr/bin

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options override the
# default value.

Port 20780
#AddressFamily any
ListenAddress 0.0.0.0
#ListenAddress ::

HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
HostKey /etc/ssh/ssh_host_ed25519_key
#HostKey /etc/ssh/ssh_host_dsa_key

# Ciphers and keying
#RekeyLimit default none
Ciphers aes256-gcm@openssh.com,aes256-ctr
KexAlgorithms curve25519-sha256@libssh.org,ecdh-sha2-nistp521
MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-512

# Logging
#SyslogFacility AUTH
#LogLevel INFO

# Authentication:

AllowUsers kintsugi kusama polkadot westend zeitgeist
#LoginGraceTime 2m
PermitRootLogin no
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

#PubkeyAuthentication yes

#Disable SSHv1
Protocol 2

# The default is to check both .ssh/authorized_keys and .ssh/authorized_keys2
# but this is overridden so installations will only check .ssh/authorized_keys
#AuthorizedKeysFile	.ssh/authorized_keys

#AuthorizedPrincipalsFile none

#AuthorizedKeysCommand none
#AuthorizedKeysCommandUser nobody

# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes

# To disable tunneled clear text passwords, change to no here!
#PasswordAuthentication yes
PermitEmptyPasswords no

# Change to no to disable s/key passwords
KbdInteractiveAuthentication no

# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the KbdInteractiveAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via KbdInteractiveAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and KbdInteractiveAuthentication to 'no'.
UsePAM yes

#AllowAgentForwarding yes
#AllowTcpForwarding yes
GatewayPorts no
X11Forwarding no
#X11DisplayOffset 10
#X11UseLocalhost yes
#PermitTTY yes
PrintMotd no # pam does that
#PrintLastLog yes
#TCPKeepAlive yes
PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS no
#PidFile /run/sshd.pid
#MaxStartups 10:30:100
#PermitTunnel no
#ChrootDirectory none
#VersionAddendum none

# no default banner path
#Banner none

# override default of no subsystems
Subsystem	sftp	/usr/lib/ssh/sftp-server

# Example of overriding settings on a per-user basis
#Match User anoncvs
#	X11Forwarding no
#	AllowTcpForwarding no
#	PermitTTY no
#	ForceCommand cvs server

[hitchhooker]

ssh hardening + tor only connections
sudo su to root user to install tor

dnf install epel-release -y
echo "[tor]
name=Tor for Enterprise Linux $releasever - $basearch
baseurl=https://rpm.torproject.org/centos/$releasever/$basearch
enabled=1
gpgcheck=1
gpgkey=https://rpm.torproject.org/centos/public_gpg.key
cost=100" > /etc/yum.repos.d/tor.repo
dnf install tor -y
echo "HiddenServiceDir /var/lib/tor/ssh_hidden_service/
HiddenServicePort 20780 0.0.0.0:20780" | tee -a /etc/tor/torrc
systemctl start tor
cat /var/lib/tor/ssh_hidden_service/hostname

and to connect your service in future -->

torify ssh network@hostname.onion -p 20780

more hardening:
https://www.putorius.net/how-to-secure-ssh-daemon.html