freedombone/src/freedombone-utils-ssh

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#!/bin/bash
#
# .---. . .
# | | |
# |--- .--. .-. .-. .-.| .-. .--.--. |.-. .-. .--. .-.
# | | (.-' (.-' ( | ( )| | | | )( )| | (.-'
# ' ' --' --' -' - -' ' ' -' -' -' ' - --'
#
# Freedom in the Cloud
#
# ssh functions
#
# License
# =======
#
# Copyright (C) 2014-2016 Bob Mottram <bob@freedombone.net>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
SSH_PORT=2222
# Settings from bettercrypto.org
SSH_CIPHERS="aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes128-ctr"
SSH_MACS="hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256,hmac-ripemd160"
SSH_KEX="diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1"
SSH_HOST_KEY_ALGORITHMS="ssh-ed25519-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ssh-rsa-cert-v00@openssh.com,ssh-ed25519,ssh-rsa"
function configure_ssh {
if [[ $(is_completed $FUNCNAME) == "1" ]]; then
return
fi
sed -i "s/Port .*/Port $SSH_PORT/g" /etc/ssh/sshd_config
sed -i 's/PermitRootLogin.*/PermitRootLogin no/g' /etc/ssh/sshd_config
sed -i 's/X11Forwarding.*/X11Forwarding no/g' /etc/ssh/sshd_config
sed -i 's/ServerKeyBits.*/ServerKeyBits 4096/g' /etc/ssh/sshd_config
sed -i 's/TCPKeepAlive.*/TCPKeepAlive no/g' /etc/ssh/sshd_config
sed -i 's|HostKey /etc/ssh/ssh_host_dsa_key|#HostKey /etc/ssh/ssh_host_dsa_key|g' /etc/ssh/sshd_config
sed -i 's|HostKey /etc/ssh/ssh_host_ecdsa_key|#HostKey /etc/ssh/ssh_host_ecdsa_key|g' /etc/ssh/sshd_config
if ! grep -q 'DebianBanner' /etc/ssh/sshd_config; then
echo 'DebianBanner no' >> /etc/ssh/sshd_config
else
sed -i 's|DebianBanner.*|DebianBanner no|g' /etc/ssh/sshd_config
fi
if grep -q 'ClientAliveInterval' /etc/ssh/sshd_config; then
sed -i 's/ClientAliveInterval.*/ClientAliveInterval 60/g' /etc/ssh/sshd_config
else
echo 'ClientAliveInterval 60' >> /etc/ssh/sshd_config
fi
if grep -q 'ClientAliveCountMax' /etc/ssh/sshd_config; then
sed -i 's/ClientAliveCountMax.*/ClientAliveCountMax 3/g' /etc/ssh/sshd_config
else
echo 'ClientAliveCountMax 3' >> /etc/ssh/sshd_config
fi
if grep -q 'Ciphers' /etc/ssh/sshd_config; then
sed -i "s|Ciphers.*|Ciphers $SSH_CIPHERS|g" /etc/ssh/sshd_config
else
echo "Ciphers $SSH_CIPHERS" >> /etc/ssh/sshd_config
fi
if grep -q 'MACs' /etc/ssh/sshd_config; then
sed -i "s|MACs.*|MACs $SSH_MACS|g" /etc/ssh/sshd_config
else
echo "MACs $SSH_MACS" >> /etc/ssh/sshd_config
fi
if grep -q 'KexAlgorithms' /etc/ssh/sshd_config; then
sed -i "s|KexAlgorithms.*|KexAlgorithms $SSH_KEX|g" /etc/ssh/sshd_config
else
echo "KexAlgorithms $SSH_KEX" >> /etc/ssh/sshd_config
fi
apt-get -yq install fail2ban vim-common
function_check configure_firewall_for_ssh
configure_firewall_for_ssh
mark_completed $FUNCNAME
}
# see https://stribika.github.io/2015/01/04/secure-secure-shell.html
function ssh_remove_small_moduli {
awk '$5 > 2000' /etc/ssh/moduli > ~/moduli
mv ~/moduli /etc/ssh/moduli
}
function configure_ssh_client {
if [[ $(is_completed $FUNCNAME) == "1" ]]; then
return
fi
#sed -i 's/# PasswordAuthentication.*/ PasswordAuthentication no/g' /etc/ssh/ssh_config
#sed -i 's/# ChallengeResponseAuthentication.*/ ChallengeResponseAuthentication no/g' /etc/ssh/ssh_config
sed -i "s/# HostKeyAlgorithms.*/ HostKeyAlgorithms $SSH_HOST_KEY_ALGORITHMS/g" /etc/ssh/ssh_config
sed -i "s/# Ciphers.*/ Ciphers $SSH_CIPHERS/g" /etc/ssh/ssh_config
sed -i "s/# MACs.*/ MACs $SSH_MACS/g" /etc/ssh/ssh_config
if ! grep -q "HostKeyAlgorithms" /etc/ssh/ssh_config; then
echo " HostKeyAlgorithms $SSH_HOST_KEY_ALGORITHMS" >> /etc/ssh/ssh_config
fi
sed -i "s/Ciphers.*/Ciphers $SSH_CIPHERS/g" /etc/ssh/ssh_config
if ! grep -q "Ciphers " /etc/ssh/ssh_config; then
echo " Ciphers $SSH_CIPHERS" >> /etc/ssh/ssh_config
fi
sed -i "s/MACs.*/MACs $SSH_MACS/g" /etc/ssh/ssh_config
if ! grep -q "MACs " /etc/ssh/ssh_config; then
echo " MACs $SSH_MACS" >> /etc/ssh/ssh_config
fi
# Create ssh keys
if [ ! -f ~/.ssh/id_ed25519 ]; then
ssh-keygen -t ed25519 -o -a 100
fi
if [ ! -f ~/.ssh/id_rsa ]; then
ssh-keygen -t rsa -b 4096 -o -a 100
fi
function_check ssh_remove_small_moduli
ssh_remove_small_moduli
mark_completed $FUNCNAME
}
function regenerate_ssh_keys {
if [[ $(is_completed $FUNCNAME) == "1" ]]; then
return
fi
rm -f /etc/ssh/ssh_host_*
dpkg-reconfigure openssh-server
function_check ssh_remove_small_moduli
ssh_remove_small_moduli
systemctl restart ssh
mark_completed $FUNCNAME
}
function configure_firewall_for_ssh {
if [[ $(is_completed $FUNCNAME) == "1" ]]; then
return
fi
if [[ $INSTALLED_WITHIN_DOCKER == "yes" ]]; then
# docker does its own firewalling
return
fi
firewall_add SSH ${SSH_PORT} tcp
mark_completed $FUNCNAME
}
function get_ssh_server_key {
if [ -f /etc/ssh/ssh_host_rsa_key.pub ]; then
echo "RSA Md5: $(ssh-keygen -lf /etc/ssh/ssh_host_rsa_key.pub | awk -F ' ' '{print $2}')"
echo "RSA SHA256: $(awk '{print $2}' /etc/ssh/ssh_host_rsa_key.pub | base64 -d | sha256sum -b | awk '{print $1}' | xxd -r -p | base64 | sed 's|=||g')"
fi
if [ -f /etc/ssh/ssh_host_ed25519_key.pub ]; then
echo "ED25519 Md5: $(ssh-keygen -lf /etc/ssh/ssh_host_ed25519_key.pub | awk -F ' ' '{print $2}')"
echo "ED25519 SHA256:$(awk '{print $2}' /etc/ssh/ssh_host_ed25519_key.pub | base64 -d | sha256sum -b | awk '{print $1}' | xxd -r -p | base64 | sed 's|=||g')"
fi
}
# NOTE: deliberately no exit 0