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#!/bin/bash
#
# Generate OpenVPN configs
#
TMP_PUSH_CONFIGFILE=$(mktemp -t vpn_push.XXXXXXX)
TMP_ROUTE_CONFIGFILE=$(mktemp -t vpn_route.XXXXXXX)
TMP_EXTRA_CONFIGFILE=$(mktemp -t vpn_extra.XXXXXXX)
#Traceback on Error and Exit come from https://docwhat.org/tracebacks-in-bash/
set -eu
_showed_traceback=f
traceback() {
# Hide the traceback() call.
local -i start=$(( ${1:-0} + 1 ))
local -i end=${#BASH_SOURCE[@]}
local -i i=0
local -i j=0
echo "Traceback (last called is first):" 1>&2
for ((i=${start}; i < ${end}; i++)); do
j=$(( $i - 1 ))
local function="${FUNCNAME[$i]}"
local file="${BASH_SOURCE[$i]}"
local line="${BASH_LINENO[$j]}"
echo " ${function}() in ${file}:${line}" 1>&2
done
}
on_error() {
local _ec="$?"
local _cmd="${BASH_COMMAND:-unknown}"
traceback 1
_showed_traceback=t
echo "The command ${_cmd} exited with exit code ${_ec}." 1>&2
}
trap on_error ERR
on_exit() {
echo "Cleaning up before Exit ..."
rm -f $TMP_PUSH_CONFIGFILE
rm -f $TMP_ROUTE_CONFIGFILE
rm -f $TMP_EXTRA_CONFIGFILE
local _ec="$?"
if [[ $_ec != 0 && "${_showed_traceback}" != t ]]; then
traceback 1
fi
}
trap on_exit EXIT
# Convert 1.2.3.4/24 -> 255.255.255.0
cidr2mask()
{
local i
local subnetmask=""
local cidr=${1#*/}
local full_octets=$(($cidr/8))
local partial_octet=$(($cidr%8))
for ((i=0;i<4;i+=1)); do
if [ $i -lt $full_octets ]; then
subnetmask+=255
elif [ $i -eq $full_octets ]; then
subnetmask+=$((256 - 2**(8-$partial_octet)))
else
subnetmask+=0
fi
[ $i -lt 3 ] && subnetmask+=.
done
echo $subnetmask
}
# Used often enough to justify a function
getroute() {
echo ${1%/*} $(cidr2mask $1)
}
usage() {
echo "usage: $0 [-d]"
echo " -u SERVER_PUBLIC_URL"
echo " [-e EXTRA_SERVER_CONFIG ]"
echo " [-E EXTRA_CLIENT_CONFIG ]"
echo " [-f FRAGMENT ]"
echo " [-n DNS_SERVER ...]"
echo " [-p PUSH ...]"
echo " [-r ROUTE ...]"
echo " [-s SERVER_SUBNET]"
echo
echo "optional arguments:"
echo " -2 Enable two factor authentication using Google Authenticator."
echo " -a Authenticate packets with HMAC using the given message digest algorithm (auth)."
echo " -b Disable 'push block-outside-dns'"
echo " -c Enable client-to-client option"
echo " -C A list of allowable TLS ciphers delimited by a colon (cipher)."
echo " -d Disable default route"
echo " -D Do not push dns servers"
echo " -k Set keepalive. Default: '10 60'"
echo " -m Set client MTU"
echo " -N Configure NAT to access external server network"
echo " -t Use TAP device (instead of TUN device)"
echo " -T Encrypt packets with the given cipher algorithm instead of the default one (tls-cipher)."
echo " -z Enable comp-lzo compression."
}
process_route_config() {
local ovpn_route_config=''
ovpn_route_config="$1"
# If user passed "0" skip this, assume no extra routes
[[ "$ovpn_route_config" == "0" ]] && break;
echo "Processing Route Config: '${ovpn_route_config}'"
[[ -n "$ovpn_route_config" ]] && echo "route $(getroute $ovpn_route_config)" >> "$TMP_ROUTE_CONFIGFILE"
}
process_push_config() {
local ovpn_push_config=''
ovpn_push_config="$1"
echo "Processing PUSH Config: '${ovpn_push_config}'"
[[ -n "$ovpn_push_config" ]] && echo "push \"$ovpn_push_config\"" >> "$TMP_PUSH_CONFIGFILE"
}
process_extra_config() {
local ovpn_extra_config=''
ovpn_extra_config="$1"
echo "Processing Extra Config: '${ovpn_extra_config}'"
[[ -n "$ovpn_extra_config" ]] && echo "$ovpn_extra_config" >> "$TMP_EXTRA_CONFIGFILE"
}
if [ "${DEBUG:-}" == "1" ]; then
set -x
fi
set -e
if [ -z "${OPENVPN:-}" ]; then
export OPENVPN="$PWD"
fi
if [ -z "${EASYRSA_PKI:-}" ]; then
export EASYRSA_PKI="$OPENVPN/pki"
fi
OVPN_AUTH=''
OVPN_CIPHER=''
OVPN_CLIENT_TO_CLIENT=''
OVPN_CN=''
OVPN_COMP_LZO=0
OVPN_DEFROUTE=1
OVPN_DEVICE="tun"
OVPN_DEVICEN=0
OVPN_DISABLE_PUSH_BLOCK_DNS=0
OVPN_DNS=1
OVPN_DNS_SERVERS=()
OVPN_ENV=${OPENVPN}/ovpn_env.sh
OVPN_EXTRA_CLIENT_CONFIG=()
OVPN_EXTRA_SERVER_CONFIG=()
OVPN_FRAGMENT=''
OVPN_KEEPALIVE="10 60"
OVPN_MTU=''
OVPN_NAT=0
OVPN_PORT=''
OVPN_PROTO=''
OVPN_PUSH=()
OVPN_ROUTES=()
OVPN_SERVER=192.168.255.0/24
OVPN_SERVER_URL=''
OVPN_TLS_CIPHER=''
# Import existing configuration if present
[ -r "$OVPN_ENV" ] && source "$OVPN_ENV"
# Parse arguments
while getopts ":a:e:E:C:T:r:s:du:bcp:n:k:DNm:f:tz2" opt; do
case $opt in
a)
OVPN_AUTH="$OPTARG"
;;
e)
mapfile -t TMP_EXTRA_SERVER_CONFIG <<< "$OPTARG"
for i in "${TMP_EXTRA_SERVER_CONFIG[@]}"; do
OVPN_EXTRA_SERVER_CONFIG+=("$i")
done
;;
E)
mapfile -t TMP_EXTRA_CLIENT_CONFIG <<< "$OPTARG"
for i in "${TMP_EXTRA_CLIENT_CONFIG[@]}"; do
OVPN_EXTRA_CLIENT_CONFIG+=("$i")
done
;;
C)
OVPN_CIPHER="$OPTARG"
;;
T)
OVPN_TLS_CIPHER="$OPTARG"
;;
r)
mapfile -t TMP_ROUTES <<< "$OPTARG"
for i in "${TMP_ROUTES[@]}"; do
OVPN_ROUTES+=("$i")
done
;;
s)
OVPN_SERVER="$OPTARG"
;;
d)
OVPN_DEFROUTE=0
OVPN_DISABLE_PUSH_BLOCK_DNS=1
;;
u)
OVPN_SERVER_URL="$OPTARG"
;;
b)
OVPN_DISABLE_PUSH_BLOCK_DNS=1
;;
c)
OVPN_CLIENT_TO_CLIENT=1
;;
p)
mapfile -t TMP_PUSH <<< "$OPTARG"
for i in "${TMP_PUSH[@]}"; do
OVPN_PUSH+=("$i")
done
;;
n)
mapfile -t TMP_DNS_SERVERS <<< "$OPTARG"
for i in "${TMP_DNS_SERVERS[@]}"; do
OVPN_DNS_SERVERS+=("$i")
done
;;
D)
OVPN_DNS=0
;;
N)
OVPN_NAT=1
;;
k)
OVPN_KEEPALIVE="$OPTARG"
;;
m)
OVPN_MTU="$OPTARG"
;;
t)
OVPN_DEVICE="tap"
;;
z)
OVPN_COMP_LZO=1
;;
2)
OVPN_OTP_AUTH=1
;;
f)
OVPN_FRAGMENT="$OPTARG"
;;
\?)
set +x
echo "Invalid option: -$OPTARG" >&2
usage
exit 1
;;
:)
set +x
echo "Option -$OPTARG requires an argument." >&2
usage
exit 1
;;
esac
done
# Create ccd directory for static routes
[ ! -d "${OPENVPN:-}/ccd" ] && mkdir -p ${OPENVPN:-}/ccd
# Server name is in the form "udp://vpn.example.com:1194"
if [[ "${OVPN_SERVER_URL:-}" =~ ^((udp|tcp|udp6|tcp6)://)?([0-9a-zA-Z\.\-]+)(:([0-9]+))?$ ]]; then
OVPN_PROTO=${BASH_REMATCH[2]};
OVPN_CN=${BASH_REMATCH[3]};
OVPN_PORT=${BASH_REMATCH[5]};
else
set +x
echo "Common name not specified, see '-u'"
usage
exit 1
fi
# Apply defaults. If dns servers were not defined with -n, use google nameservers
set +u
[ -z "$OVPN_DNS_SERVERS" ] && OVPN_DNS_SERVERS=("8.8.8.8" "8.8.4.4")
[ -z "$OVPN_PROTO" ] && OVPN_PROTO=udp
[ -z "$OVPN_PORT" ] && OVPN_PORT=1194
set -u
[ "${#OVPN_ROUTES[@]}" == "0" ] && [ "$OVPN_DEFROUTE" == "1" ] && OVPN_ROUTES+=("192.168.254.0/24")
# Preserve config
if [ -f "$OVPN_ENV" ]; then
bak_env=$OVPN_ENV.$(date +%s).bak
echo "Backing up $OVPN_ENV -> $bak_env"
mv "$OVPN_ENV" "$bak_env"
fi
# Save the current OVPN_ vars to the ovpn_env.sh file
(set | grep '^OVPN_') | while read -r var; do
echo "declare -x $var" >> "$OVPN_ENV"
done
conf=${OPENVPN:-}/openvpn.conf
if [ -f "$conf" ]; then
bak=$conf.$(date +%s).bak
echo "Backing up $conf -> $bak"
mv "$conf" "$bak"
fi
# Echo extra client configurations
if [ ${#OVPN_EXTRA_CLIENT_CONFIG[@]} -gt 0 ]; then
for i in "${OVPN_EXTRA_CLIENT_CONFIG[@]}"; do
echo "Processing Extra Client Config: $i"
done
fi
cat > "$conf" <<EOF
server $(getroute $OVPN_SERVER)
verb 3
key $EASYRSA_PKI/private/${OVPN_CN}.key
ca $EASYRSA_PKI/ca.crt
cert $EASYRSA_PKI/issued/${OVPN_CN}.crt
dh $EASYRSA_PKI/dh.pem
tls-auth $EASYRSA_PKI/ta.key
key-direction 0
keepalive $OVPN_KEEPALIVE
persist-key
persist-tun
proto $OVPN_PROTO
# Rely on Docker to do port mapping, internally always 1194
port 1194
dev $OVPN_DEVICE$OVPN_DEVICEN
status /tmp/openvpn-status.log
user nobody
group nogroup
EOF
if [ "${OVPN_DISABLE_PUSH_BLOCK_DNS}" == "1" ]; then
echo "Disable default push of 'block-outside-dns'"
else
process_push_config "block-outside-dns"
fi
[ -n "$OVPN_TLS_CIPHER" ] && echo "tls-cipher $OVPN_TLS_CIPHER" >> "$conf"
[ -n "$OVPN_CIPHER" ] && echo "cipher $OVPN_CIPHER" >> "$conf"
[ -n "$OVPN_AUTH" ] && echo "auth $OVPN_AUTH" >> "$conf"
[ -n "${OVPN_CLIENT_TO_CLIENT:-}" ] && echo "client-to-client" >> "$conf"
[ "$OVPN_COMP_LZO" == "1" ] && echo "comp-lzo" >> "$conf"
[ "$OVPN_COMP_LZO" == "0" ] && echo "comp-lzo no" >> "$conf"
[ -n "${OVPN_FRAGMENT:-}" ] && echo "fragment $OVPN_FRAGMENT" >> "$conf"
# Append route commands
if [ ${#OVPN_ROUTES[@]} -gt 0 ]; then
for i in "${OVPN_ROUTES[@]}"; do
process_route_config "$i"
done
echo -e "\n### Route Configurations Below" >> "$conf"
cat $TMP_ROUTE_CONFIGFILE >> "$conf"
fi
# Append push commands
[ "$OVPN_DNS" == "1" ] && for i in "${OVPN_DNS_SERVERS[@]}"; do
process_push_config "dhcp-option DNS $i"
done
if [ "$OVPN_COMP_LZO" == "0" ]; then
process_push_config "comp-lzo no"
fi
[ ${#OVPN_PUSH[@]} -gt 0 ] && for i in "${OVPN_PUSH[@]}"; do
process_push_config "$i"
done
echo -e "\n### Push Configurations Below" >> "$conf"
cat $TMP_PUSH_CONFIGFILE >> "$conf"
# Append optional OTP authentication support
if [ -n "${OVPN_OTP_AUTH:-}" ]; then
echo -e "\n\n# Enable OTP+PAM for user authentication" >> "$conf"
echo "plugin /usr/lib/openvpn/plugins/openvpn-plugin-auth-pam.so openvpn" >> "$conf"
echo "reneg-sec 0" >> "$conf"
fi
# Append extra server configurations
if [ ${#OVPN_EXTRA_SERVER_CONFIG[@]} -gt 0 ]; then
for i in "${OVPN_EXTRA_SERVER_CONFIG[@]}"; do
process_extra_config "$i"
done
echo -e "\n### Extra Configurations Below" >> "$conf"
cat $TMP_EXTRA_CONFIGFILE >> "$conf"
fi
set +e
# Clean-up duplicate configs
if diff -q "${bak_env:-}" "$OVPN_ENV" 2>/dev/null; then
echo "Removing duplicate back-up: $bak_env"
rm -fv "$bak_env"
fi
if diff -q "${bak:-}" "$conf" 2>/dev/null; then
echo "Removing duplicate back-up: $bak"
rm -fv "$bak"
fi
echo "Successfully generated config"