--- /dev/null
+# $OpenBSD: sshd_config,v 1.103 2018/04/09 20:41:22 tj Exp $
+
+# This is the sshd server system-wide configuration file. See
+# sshd_config(5) for more information.
+
+# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin
+
+# 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.
+
+Include /etc/ssh/sshd_config.d/*.conf
+
+#Port 22
+#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
+
+# Ciphers and keying
+#RekeyLimit default none
+
+# Logging
+#SyslogFacility AUTH
+#LogLevel INFO
+
+# Authentication:
+
+#LoginGraceTime 2m
+PermitRootLogin no # plomlompom's security rule
+#StrictModes yes
+#MaxAuthTries 6
+#MaxSessions 10
+
+#PubkeyAuthentication yes
+
+# Expect .ssh/authorized_keys2 to be disregarded by default in future.
+#AuthorizedKeysFile .ssh/authorized_keys .ssh/authorized_keys2
+
+#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 no
+#PermitEmptyPasswords no
+
+# Change to yes to enable challenge-response passwords (beware issues with
+# some PAM modules and threads)
+ChallengeResponseAuthentication no
+
+# Kerberos options
+#KerberosAuthentication no
+#KerberosOrLocalPasswd yes
+#KerberosTicketCleanup yes
+#KerberosGetAFSToken no
+
+# GSSAPI options
+#GSSAPIAuthentication no
+#GSSAPICleanupCredentials yes
+#GSSAPIStrictAcceptorCheck yes
+#GSSAPIKeyExchange no
+
+# Set this to 'yes' to enable PAM authentication, account processing,
+# and session processing. If this is enabled, PAM authentication will
+# be allowed through the ChallengeResponseAuthentication and
+# PasswordAuthentication. Depending on your PAM configuration,
+# PAM authentication via ChallengeResponseAuthentication may bypass
+# the setting of "PermitRootLogin yes
+# If you just want the PAM account and session checks to run without
+# PAM authentication, then enable this but set PasswordAuthentication
+# and ChallengeResponseAuthentication to 'no'.
+UsePAM yes
+
+#AllowAgentForwarding yes
+#AllowTcpForwarding yes
+#GatewayPorts no
+X11Forwarding yes
+#X11DisplayOffset 10
+#X11UseLocalhost yes
+#PermitTTY yes
+PrintMotd no
+#PrintLastLog yes
+#TCPKeepAlive yes
+#PermitUserEnvironment no
+#Compression delayed
+#ClientAliveInterval 0
+#ClientAliveCountMax 3
+#UseDNS no
+#PidFile /var/run/sshd.pid
+#MaxStartups 10:30:100
+#PermitTunnel no
+#ChrootDirectory none
+#VersionAddendum none
+
+# no default banner path
+#Banner none
+
+# Allow client to pass locale environment variables
+AcceptEnv LANG LC_*
+
+# override default of no subsystems
+Subsystem sftp /usr/lib/openssh/sftp-server
+
+# Example of overriding settings on a per-user basis
+#Match User anoncvs
+# X11Forwarding no
+# AllowTcpForwarding no
+# PermitTTY no
+# ForceCommand cvs server
+ClientAliveInterval 120
--- /dev/null
+#!/bin/sh
+# This script turns a fresh server with password-based root access into
+# one of only key-based access and only to new non-root account plom.
+#
+# CAUTION: This is optimized for a *fresh* setup. It will overwrite any
+# pre-existing ~/.ssh/authorized_keys of user plom with one that solely
+# contains the local ~/.ssh/id_rsa.pub, and also any old
+# /etc/ssh/sshd_config.
+#
+# Dependencies: ssh, scp, sshpass, ~/.ssh/id_rsa.pub, properly
+# configured sshd_config file in reach.
+set -e
+set -x
+
+# Location of an sshd_config with "PermitRootLogin no" and
+# "PasswordAuthentication no".
+config_tree_prefix="${HOME}/public_repos/config/bullseye"
+linkable_files_dir="${config_tree_prefix}/etc_files/server"
+system_path_sshd_config='/etc/ssh/sshd_config'
+local_path_sshd_config="${linkable_files_dir}${system_path_sshd_config}"
+
+# Ensure we have a server name as argument.
+if [ $# -eq 0 ]; then
+ echo "Need server as argument."
+ false
+fi
+server="$1"
+
+# This will be used to log-in as root from plom account.
+echo 'First, enter the old root password; then enter new password twice.'
+ssh root@"${server}" "passwd"
+
+# Save root password for sshpass
+stty -echo
+printf "Re-enter new server root password: "
+read PW_ROOT
+stty echo
+printf "\n"
+export SSHPASS="${PW_ROOT}"
+
+# Create user plom, and his ~/.ssh/authorized_keys based on the local
+# ~/.ssh/id_rsa.pub; ensure the result has proper permissions and
+# ownerships. Then disable root and pw login by copying over the
+# sshd_config and restart ssh daemon.
+#
+# This could be a line or two shorter by using ssh-copy-id, but that
+# would require setting a password for user plom otherwise not needed.
+sshpass -e scp ~/.ssh/id_rsa.pub root@"${server}":/tmp/authorized_keys
+sshpass -e ssh root@"${server}" \
+ 'useradd -m plom && '\
+ 'mkdir /home/plom/.ssh && '\
+ 'chown plom:plom /home/plom/.ssh && '\
+ 'chown plom:plom /tmp/authorized_keys && '\
+ 'chmod u=rw,go= /tmp/authorized_keys && '\
+ 'mv /tmp/authorized_keys /home/plom/.ssh/'
+sshpass -e scp "${local_path_sshd_config}" root@"${server}":"${system_path_sshd_config}"
+sshpass -e ssh root@"${server}" 'service ssh restart'
--- /dev/null
+#!/bin/sh
+# This script assumes a server with key-based root access into one of
+# key-based access only to a new non-root account plom.
+#
+# CAUTION: This is optimized for a *fresh* setup. It will overwrite any
+# old /etc/ssh/sshd_config.
+#
+# Dependencies: ssh, scp, properly configured sshd_config file in reach.
+set -e
+
+# Location of an sshd_config with "PermitRootLogin no" and
+# "PasswordAuthentication no".
+config_tree_prefix="${HOME}/public_repos/config/bullseye"
+linkable_files_dir="${config_tree_prefix}/etc_files/server"
+system_path_sshd_config='/etc/ssh/sshd_config'
+local_path_sshd_config="${linkable_files_dir}${system_path_sshd_config}"
+
+# Ensure we have a server name as argument.
+if [ $# -eq 0 ]; then
+ echo "Need server as argument."
+ false
+fi
+server="$1"
+
+# So we're only asked once …
+eval $(ssh-agent)
+ssh-add
+
+# This will be used to log-in as root from plom account.
+echo 'Asking for new root password.'
+ssh root@"${server}" "passwd"
+
+# Set up plom's ~/.ssh/authorized_keys from root's.
+ssh root@"${server}" 'useradd -m plom'
+ssh root@"${server}" 'mkdir /home/plom/.ssh'
+ssh root@"${server}" 'chown plom:plom /home/plom/.ssh'
+ssh root@"${server}" 'cp /root/.ssh/authorized_keys /home/plom/.ssh/'
+ssh root@"${server}" 'chown plom:plom /home/plom/.ssh/authorized_keys'
+
+# Set up SSH config and remove direct SSH login to root.
+scp "${local_path_sshd_config}" root@"${server}":"${system_path_sshd_config}"
+ssh root@"${server}" 'rm -rf /root/.ssh && service ssh restart'
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