extra script to add further users to the vpn, these do not need to be system users on the server. Only tested on raspberry pi

extras/add_vpn_user.sh

@@ -0,0 +1,54 @@
+#!/bin/bash
+
+exiterr()  { echo "Error: $1" >&2; exit 1; }
+conf_bk() { /bin/cp -f "$1" "$1.old-$SYS_DT" 2>/dev/null; }
+del_vpn_user() {
+lineno=$(grep -n $1 $2 | cut -d : -f1)
+sed -i "${lineno}d" $2
+}
+
+VPN_USER=$1
+VPN_PASSWORD=$2
+
+if [ -z "$VPN_USER" ] || [ -z "$VPN_PASSWORD" ]; then
+  exiterr "All VPN credentials must be specified. Usage: add_vpn_user.sh 'user' 'password' "
+fi
+
+if printf '%s' "$VPN_USER $VPN_PASSWORD" | LC_ALL=C grep -q '[^ -~]\+'; then
+  exiterr "VPN credentials must not contain non-ASCII characters."
+fi
+
+case "$VPN_USER $VPN_PASSWORD" in
+  *[\\\"\']*)
+    exiterr "VPN credentials must not contain these special characters: \\ \" '"
+    ;;
+esac
+
+# Create VPN credentials
+conf_bk "/etc/ppp/chap-secrets"
+# delete any existing line for this user first
+lineno=$(grep -n "^\"$VPN_USER\" " /etc/ppp/chap-secrets | cut -d : -f1)
+sed -i "${lineno}d" $2
+[ -z $lineno ] || sed -i "${lineno}d" /etc/ppp/chap-secrets
+# append a line for the user with the new password
+cat >> /etc/ppp/chap-secrets <<EOF
+"$VPN_USER" l2tpd "$VPN_PASSWORD" *
+EOF
+
+conf_bk "/etc/ipsec.d/passwd"
+# delete any existing line for this user first
+lineno=$(grep -n "^$VPN_USER:" /etc/ipsec.d/passwd | cut -d : -f1)
+sed -i "${lineno}d" $2
+[ -z $lineno ] || sed -i "${lineno}d" /etc/ipsec.d/passwd
+# append a line for the user with the new password
+VPN_PASSWORD_ENC=$(openssl passwd -1 "$VPN_PASSWORD")
+cat >> /etc/ipsec.d/passwd <<EOF
+$VPN_USER:$VPN_PASSWORD_ENC:xauth-psk
+EOF
+
+echo "Added a vpn user"
+echo "  User: $VPN_USER"
+echo "  Password: $VPN_PASSWORD"
+echo "to /etc/ppp/chap-secrets and /etc/ipsec.d/passwd"
+echo
+