#!/bin/bash # # Script for automatic setup of an IPsec VPN server on Alpine Linux # Works on any dedicated server or virtual private server (VPS) # # DO NOT RUN THIS SCRIPT ON YOUR PC OR MAC! # # The latest version of this script is available at: # https://github.com/hwdsl2/setup-ipsec-vpn # # Copyright (C) 2021-2022 Lin Song <linsongui@gmail.com> # # This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 # Unported License: http://creativecommons.org/licenses/by-sa/3.0/ # # Attribution required: please include my name in any derivative and let me # know how you have improved it! # ===================================================== # Define your own values for these variables # - IPsec pre-shared key, VPN username and password # - All values MUST be placed inside 'single quotes' # - DO NOT use these special characters within values: \ " ' YOUR_IPSEC_PSK='' YOUR_USERNAME='' YOUR_PASSWORD='' # Important notes: https://git.io/vpnnotes # Setup VPN clients: https://git.io/vpnclients # IKEv2 guide: https://git.io/ikev2 # ===================================================== export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin" SYS_DT=$(date +%F-%T | tr ':' '_') exiterr() { echo "Error: $1" >&2; exit 1; } exiterr2() { exiterr "'apk add' failed."; } conf_bk() { /bin/cp -f "$1" "$1.old-$SYS_DT" 2>/dev/null; } bigecho() { echo "## $1"; } check_ip() { IP_REGEX='^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$' printf '%s' "$1" | tr -d '\n' | grep -Eq "$IP_REGEX" } check_dns_name() { FQDN_REGEX='^([a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)+[a-zA-Z]{2,}$' printf '%s' "$1" | tr -d '\n' | grep -Eq "$FQDN_REGEX" } check_root() { if [ "$(id -u)" != 0 ]; then exiterr "Script must be run as root. Try 'sudo bash $0'" fi } check_vz() { if [ -f /proc/user_beancounters ]; then exiterr "OpenVZ VPS is not supported." fi } check_os() { os_type=$(lsb_release -si 2>/dev/null) [ -z "$os_type" ] && [ -f /etc/os-release ] && os_type=$(. /etc/os-release && printf '%s' "$ID") case $os_type in [Aa]lpine) os_type=alpine ;; *) exiterr "This script only supports Alpine Linux." ;; esac os_ver=$(. /etc/os-release && printf '%s' "$VERSION_ID" | cut -d '.' -f 1,2) if [ "$os_ver" != "3.14" ] && [ "$os_ver" != "3.15" ]; then exiterr "This script only supports Alpine Linux 3.14/3.15." fi } check_iface() { def_iface=$(route 2>/dev/null | grep -m 1 '^default' | grep -o '[^ ]*$') def_state=$(cat "/sys/class/net/$def_iface/operstate" 2>/dev/null) if [ -n "$def_state" ] && [ "$def_state" != "down" ]; then if ! uname -m | grep -qi -e '^arm' -e '^aarch64'; then case $def_iface in wl*) exiterr "Wireless interface '$def_iface' detected. DO NOT run this script on your PC or Mac!" ;; esac fi NET_IFACE="$def_iface" else eth0_state=$(cat "/sys/class/net/eth0/operstate" 2>/dev/null) if [ -z "$eth0_state" ] || [ "$eth0_state" = "down" ]; then exiterr "Could not detect the default network interface." fi NET_IFACE=eth0 fi } check_creds() { [ -n "$YOUR_IPSEC_PSK" ] && VPN_IPSEC_PSK="$YOUR_IPSEC_PSK" [ -n "$YOUR_USERNAME" ] && VPN_USER="$YOUR_USERNAME" [ -n "$YOUR_PASSWORD" ] && VPN_PASSWORD="$YOUR_PASSWORD" if [ -z "$VPN_IPSEC_PSK" ] && [ -z "$VPN_USER" ] && [ -z "$VPN_PASSWORD" ]; then bigecho "VPN credentials not set by user. Generating random PSK and password..." VPN_IPSEC_PSK=$(LC_CTYPE=C tr -dc 'A-HJ-NPR-Za-km-z2-9' </dev/urandom 2>/dev/null | head -c 20) VPN_USER=vpnuser VPN_PASSWORD=$(LC_CTYPE=C tr -dc 'A-HJ-NPR-Za-km-z2-9' </dev/urandom 2>/dev/null | head -c 16) fi if [ -z "$VPN_IPSEC_PSK" ] || [ -z "$VPN_USER" ] || [ -z "$VPN_PASSWORD" ]; then exiterr "All VPN credentials must be specified. Edit the script and re-enter them." fi if printf '%s' "$VPN_IPSEC_PSK $VPN_USER $VPN_PASSWORD" | LC_ALL=C grep -q '[^ -~]\+'; then exiterr "VPN credentials must not contain non-ASCII characters." fi case "$VPN_IPSEC_PSK $VPN_USER $VPN_PASSWORD" in *[\\\"\']*) exiterr "VPN credentials must not contain these special characters: \\ \" '" ;; esac } check_dns() { if { [ -n "$VPN_DNS_SRV1" ] && ! check_ip "$VPN_DNS_SRV1"; } \ || { [ -n "$VPN_DNS_SRV2" ] && ! check_ip "$VPN_DNS_SRV2"; }; then exiterr "The DNS server specified is invalid." fi } check_server_dns() { if [ -n "$VPN_DNS_NAME" ] && ! check_dns_name "$VPN_DNS_NAME"; then exiterr "Invalid DNS name. 'VPN_DNS_NAME' must be a fully qualified domain name (FQDN)." fi } check_client_name() { if [ -n "$VPN_CLIENT_NAME" ]; then name_len="$(printf '%s' "$VPN_CLIENT_NAME" | wc -m)" if [ "$name_len" -gt "64" ] || printf '%s' "$VPN_CLIENT_NAME" | LC_ALL=C grep -q '[^A-Za-z0-9_-]\+' \ || case $VPN_CLIENT_NAME in -*) true;; *) false;; esac; then exiterr "Invalid client name. Use one word only, no special characters except '-' and '_'." fi fi } start_setup() { bigecho "VPN setup in progress... Please be patient." mkdir -p /opt/src cd /opt/src || exit 1 } install_setup_pkgs() { bigecho "Installing packages required for setup..." ( set -x apk add -U -q bash bind-tools coreutils openssl wget iproute2 sed grep ) || exiterr2 } detect_ip() { bigecho "Trying to auto discover IP of this server..." public_ip=${VPN_PUBLIC_IP:-''} check_ip "$public_ip" || public_ip=$(dig @resolver1.opendns.com -t A -4 myip.opendns.com +short) check_ip "$public_ip" || public_ip=$(wget -t 3 -T 15 -qO- http://ipv4.icanhazip.com) check_ip "$public_ip" || exiterr "Cannot detect this server's public IP. Define it as variable 'VPN_PUBLIC_IP' and re-run this script." } install_vpn_pkgs() { bigecho "Installing packages required for the VPN..." ( set -x apk add -U -q libcap-ng libcurl libevent linux-pam musl nspr nss nss-tools \ bison flex gcc make libc-dev bsd-compat-headers linux-pam-dev nss-dev \ libcap-ng-dev libevent-dev curl-dev nspr-dev uuidgen openrc xl2tpd ) || exiterr2 } install_fail2ban() { bigecho "Installing Fail2Ban to protect SSH..." ( set -x apk add -U -q fail2ban ) || exiterr2 } get_helper_scripts() { bigecho "Downloading helper scripts..." base_url="https://github.com/hwdsl2/setup-ipsec-vpn/raw/master/extras" ikev2_url="$base_url/ikev2setup.sh" add_url="$base_url/add_vpn_user.sh" del_url="$base_url/del_vpn_user.sh" cd /opt/src || exit 1 printf '%s' "+ " for sc in ikev2.sh addvpnuser.sh delvpnuser.sh; do [ "$sc" = "ikev2.sh" ] && dl_url="$ikev2_url" [ "$sc" = "addvpnuser.sh" ] && dl_url="$add_url" [ "$sc" = "delvpnuser.sh" ] && dl_url="$del_url" printf '%s' "$sc " wget -t 3 -T 30 -q -O "$sc" "$dl_url" || /bin/rm -f "$sc" [ -s "$sc" ] && chmod +x "$sc" && ln -s "/opt/src/$sc" /usr/bin 2>/dev/null done echo } get_swan_ver() { SWAN_VER=4.6 base_url="https://github.com/hwdsl2/vpn-extras/releases/download/v1.0.0" swan_ver_url="$base_url/v1-$os_type-$os_ver-swanver" swan_ver_latest=$(wget -t 3 -T 15 -qO- "$swan_ver_url" | head -n 1) if printf '%s' "$swan_ver_latest" | grep -Eq '^([3-9]|[1-9][0-9]{1,2})(\.([0-9]|[1-9][0-9]{1,2})){1,2}$'; then SWAN_VER="$swan_ver_latest" fi } check_libreswan() { ipsec_ver=$(/usr/local/sbin/ipsec --version 2>/dev/null) swan_ver_old=$(printf '%s' "$ipsec_ver" | sed -e 's/.*Libreswan U\?//' -e 's/\( (\|\/K\).*//') ipsec_bin="/usr/local/sbin/ipsec" if [ -n "$swan_ver_old" ] && printf '%s' "$ipsec_ver" | grep -qi 'libreswan' \ && [ "$(find "$ipsec_bin" -mmin -10080)" ]; then return 0 fi get_swan_ver if [ -s "$ipsec_bin" ] && [ "$swan_ver_old" = "$SWAN_VER" ]; then touch "$ipsec_bin" fi [ "$swan_ver_old" = "$SWAN_VER" ] } get_libreswan() { if ! check_libreswan; then bigecho "Downloading Libreswan..." cd /opt/src || exit 1 swan_file="libreswan-$SWAN_VER.tar.gz" swan_url1="https://github.com/libreswan/libreswan/archive/v$SWAN_VER.tar.gz" swan_url2="https://download.libreswan.org/$swan_file" ( set -x wget -t 3 -T 30 -q -O "$swan_file" "$swan_url1" || wget -t 3 -T 30 -q -O "$swan_file" "$swan_url2" ) || exit 1 /bin/rm -rf "/opt/src/libreswan-$SWAN_VER" tar xzf "$swan_file" && /bin/rm -f "$swan_file" else bigecho "Libreswan $swan_ver_old is already installed, skipping..." fi } install_libreswan() { if ! check_libreswan; then bigecho "Compiling and installing Libreswan, please wait..." cd "libreswan-$SWAN_VER" || exit 1 sed -i '28s/stdlib\.h/sys\/types.h/' include/fd.h cat > Makefile.inc.local <<'EOF' WERROR_CFLAGS=-w -s USE_DNSSEC=false USE_DH2=true FINALNSSDIR=/etc/ipsec.d USE_GLIBC_KERN_FLIP_HEADERS=true EOF NPROCS=$(grep -c ^processor /proc/cpuinfo) [ -z "$NPROCS" ] && NPROCS=1 ( set -x make "-j$((NPROCS+1))" -s base >/dev/null && make -s install-base >/dev/null ) cd /opt/src || exit 1 /bin/rm -rf "/opt/src/libreswan-$SWAN_VER" if ! /usr/local/sbin/ipsec --version 2>/dev/null | grep -qF "$SWAN_VER"; then exiterr "Libreswan $SWAN_VER failed to build." fi fi } create_vpn_config() { bigecho "Creating VPN configuration..." L2TP_NET=${VPN_L2TP_NET:-'192.168.42.0/24'} L2TP_LOCAL=${VPN_L2TP_LOCAL:-'192.168.42.1'} L2TP_POOL=${VPN_L2TP_POOL:-'192.168.42.10-192.168.42.250'} XAUTH_NET=${VPN_XAUTH_NET:-'192.168.43.0/24'} XAUTH_POOL=${VPN_XAUTH_POOL:-'192.168.43.10-192.168.43.250'} DNS_SRV1=${VPN_DNS_SRV1:-'8.8.8.8'} DNS_SRV2=${VPN_DNS_SRV2:-'8.8.4.4'} DNS_SRVS="\"$DNS_SRV1 $DNS_SRV2\"" [ -n "$VPN_DNS_SRV1" ] && [ -z "$VPN_DNS_SRV2" ] && DNS_SRVS="$DNS_SRV1" # Create IPsec config conf_bk "/etc/ipsec.conf" cat > /etc/ipsec.conf <<EOF version 2.0 config setup virtual-private=%v4:10.0.0.0/8,%v4:192.168.0.0/16,%v4:172.16.0.0/12,%v4:!$L2TP_NET,%v4:!$XAUTH_NET uniqueids=no conn shared left=%defaultroute leftid=$public_ip right=%any encapsulation=yes authby=secret pfs=no rekey=no keyingtries=5 dpddelay=30 dpdtimeout=120 dpdaction=clear ikev2=never ike=aes256-sha2,aes128-sha2,aes256-sha1,aes128-sha1,aes256-sha2;modp1024,aes128-sha1;modp1024 phase2alg=aes_gcm-null,aes128-sha1,aes256-sha1,aes256-sha2_512,aes128-sha2,aes256-sha2 ikelifetime=24h salifetime=24h sha2-truncbug=no conn l2tp-psk auto=add leftprotoport=17/1701 rightprotoport=17/%any type=transport also=shared conn xauth-psk auto=add leftsubnet=0.0.0.0/0 rightaddresspool=$XAUTH_POOL modecfgdns=$DNS_SRVS leftxauthserver=yes rightxauthclient=yes leftmodecfgserver=yes rightmodecfgclient=yes modecfgpull=yes cisco-unity=yes also=shared include /etc/ipsec.d/*.conf EOF if uname -m | grep -qi '^arm'; then if ! modprobe -q sha512; then sed -i '/phase2alg/s/,aes256-sha2_512//' /etc/ipsec.conf fi fi # Specify IPsec PSK conf_bk "/etc/ipsec.secrets" cat > /etc/ipsec.secrets <<EOF %any %any : PSK "$VPN_IPSEC_PSK" EOF # Create xl2tpd config conf_bk "/etc/xl2tpd/xl2tpd.conf" cat > /etc/xl2tpd/xl2tpd.conf <<EOF [global] port = 1701 [lns default] ip range = $L2TP_POOL local ip = $L2TP_LOCAL require chap = yes refuse pap = yes require authentication = yes name = l2tpd pppoptfile = /etc/ppp/options.xl2tpd length bit = yes EOF # Set xl2tpd options conf_bk "/etc/ppp/options.xl2tpd" cat > /etc/ppp/options.xl2tpd <<EOF +mschap-v2 ipcp-accept-local ipcp-accept-remote noccp auth mtu 1280 mru 1280 proxyarp lcp-echo-failure 4 lcp-echo-interval 30 connect-delay 5000 ms-dns $DNS_SRV1 EOF if [ -z "$VPN_DNS_SRV1" ] || [ -n "$VPN_DNS_SRV2" ]; then cat >> /etc/ppp/options.xl2tpd <<EOF ms-dns $DNS_SRV2 EOF fi # Create VPN credentials conf_bk "/etc/ppp/chap-secrets" cat > /etc/ppp/chap-secrets <<EOF "$VPN_USER" l2tpd "$VPN_PASSWORD" * EOF conf_bk "/etc/ipsec.d/passwd" VPN_PASSWORD_ENC=$(openssl passwd -1 "$VPN_PASSWORD") cat > /etc/ipsec.d/passwd <<EOF $VPN_USER:$VPN_PASSWORD_ENC:xauth-psk EOF } update_sysctl() { bigecho "Updating sysctl settings..." if ! grep -qs "hwdsl2 VPN script" /etc/sysctl.conf; then conf_bk "/etc/sysctl.conf" cat >> /etc/sysctl.conf <<EOF # Added by hwdsl2 VPN script kernel.msgmnb = 65536 kernel.msgmax = 65536 net.ipv4.ip_forward = 1 net.ipv4.conf.all.accept_redirects = 0 net.ipv4.conf.all.send_redirects = 0 net.ipv4.conf.all.rp_filter = 0 net.ipv4.conf.default.accept_redirects = 0 net.ipv4.conf.default.send_redirects = 0 net.ipv4.conf.default.rp_filter = 0 net.ipv4.conf.$NET_IFACE.send_redirects = 0 net.ipv4.conf.$NET_IFACE.rp_filter = 0 net.core.wmem_max = 12582912 net.core.rmem_max = 12582912 net.ipv4.tcp_rmem = 10240 87380 12582912 net.ipv4.tcp_wmem = 10240 87380 12582912 EOF fi } update_iptables() { bigecho "Updating IPTables rules..." IPT_FILE=/etc/iptables.rules ipt_flag=0 if ! grep -qs "hwdsl2 VPN script" "$IPT_FILE"; then ipt_flag=1 fi ipi='iptables -I INPUT' ipf='iptables -I FORWARD' ipp='iptables -t nat -I POSTROUTING' res='RELATED,ESTABLISHED' if [ "$ipt_flag" = "1" ]; then service fail2ban stop >/dev/null 2>&1 iptables-save > "$IPT_FILE.old-$SYS_DT" $ipi 1 -p udp --dport 1701 -m policy --dir in --pol none -j DROP $ipi 2 -m conntrack --ctstate INVALID -j DROP $ipi 3 -m conntrack --ctstate "$res" -j ACCEPT $ipi 4 -p udp -m multiport --dports 500,4500 -j ACCEPT $ipi 5 -p udp --dport 1701 -m policy --dir in --pol ipsec -j ACCEPT $ipi 6 -p udp --dport 1701 -j DROP $ipf 1 -m conntrack --ctstate INVALID -j DROP $ipf 2 -i "$NET_IFACE" -o ppp+ -m conntrack --ctstate "$res" -j ACCEPT $ipf 3 -i ppp+ -o "$NET_IFACE" -j ACCEPT $ipf 4 -i ppp+ -o ppp+ -j ACCEPT $ipf 5 -i "$NET_IFACE" -d "$XAUTH_NET" -m conntrack --ctstate "$res" -j ACCEPT $ipf 6 -s "$XAUTH_NET" -o "$NET_IFACE" -j ACCEPT $ipf 7 -s "$XAUTH_NET" -o ppp+ -j ACCEPT iptables -A FORWARD -j DROP $ipp -s "$XAUTH_NET" -o "$NET_IFACE" -m policy --dir out --pol none -j MASQUERADE $ipp -s "$L2TP_NET" -o "$NET_IFACE" -j MASQUERADE echo "# Modified by hwdsl2 VPN script" > "$IPT_FILE" iptables-save >> "$IPT_FILE" fi } enable_on_boot() { bigecho "Enabling services on boot..." mkdir -p /etc/network/if-pre-up.d cat > /etc/network/if-pre-up.d/iptablesload <<'EOF' #!/bin/sh iptables-restore < /etc/iptables.rules exit 0 EOF chmod +x /etc/network/if-pre-up.d/iptablesload sed -i '1c\#!/sbin/openrc-run' /etc/init.d/ipsec for svc in fail2ban ipsec xl2tpd; do rc-update add "$svc" default >/dev/null done } start_services() { bigecho "Starting services..." sysctl -e -q -p chmod +x /etc/rc.local chmod 600 /etc/ipsec.secrets* /etc/ppp/chap-secrets* /etc/ipsec.d/passwd* mkdir -p /run/pluto service fail2ban restart >/dev/null 2>&1 service ipsec restart >/dev/null 2>&1 service xl2tpd restart >/dev/null 2>&1 } show_vpn_info() { cat <<EOF ================================================ IPsec VPN server is now ready for use! Connect to your new VPN with these details: Server IP: $public_ip IPsec PSK: $VPN_IPSEC_PSK Username: $VPN_USER Password: $VPN_PASSWORD Write these down. You'll need them to connect! Important notes: https://git.io/vpnnotes Setup VPN clients: https://git.io/vpnclients IKEv2 guide: https://git.io/ikev2 ================================================ EOF } set_up_ikev2() { status=0 if [ -s /opt/src/ikev2.sh ] && [ ! -f /etc/ipsec.d/ikev2.conf ]; then sleep 1 VPN_DNS_NAME="$VPN_DNS_NAME" VPN_PUBLIC_IP="$public_ip" \ VPN_CLIENT_NAME="$VPN_CLIENT_NAME" VPN_XAUTH_POOL="$VPN_XAUTH_POOL" \ VPN_DNS_SRV1="$VPN_DNS_SRV1" VPN_DNS_SRV2="$VPN_DNS_SRV2" \ VPN_PROTECT_CONFIG="$VPN_PROTECT_CONFIG" \ /bin/bash /opt/src/ikev2.sh --auto || status=1 elif [ -s /opt/src/ikev2.sh ]; then cat <<'EOF' ================================================ IKEv2 is already set up on this server. To manage IKEv2 clients, run: sudo ikev2.sh ================================================ EOF fi } vpnsetup() { check_root check_vz check_os check_iface check_creds check_dns check_server_dns check_client_name start_setup install_setup_pkgs detect_ip install_vpn_pkgs install_fail2ban get_helper_scripts get_libreswan install_libreswan create_vpn_config update_sysctl update_iptables enable_on_boot start_services show_vpn_info set_up_ikev2 } ## Defer setup until we have the complete script vpnsetup "$@" exit "$status"