CentOS7部署l2tp/IPsec服务

1、安装必要的工具

yum install vim net-tools wget unzip -y

2. 下载安装脚本

wget -O StackScript.zip http://files.cnblogs.com/files/think8848/StackScript.zip

3. 解压文件

unzip StackScript.zip

4. 执行安装文件

chmod +x StackScript
 
./StackScript

StackScript实际上市判断你的系统版本，然后下载安装脚本执行安装，centos安装的脚本如下：

#!/bin/sh
#
# Script for automatic setup of an IPsec VPN server on CentOS/RHEL 6 and 7.
# Works on any dedicated server or virtual private server (VPS) except OpenVZ.
#
# 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) 2015-2017 Lin Song <linsongui@gmail.com>
# Based on the work of Thomas Sarlandie (Copyright 2012)
#
# 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
 
# =====================================================
 
export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
SYS_DT="$(date +%F-%T)"
 
exiterr()  { echo "Error: $1" >&2; exit 1; }
exiterr2() { exiterr "'yum install' failed."; }
conf_bk() { /bin/cp -f "$1" "$1.old-$SYS_DT" 2>/dev/null; }
bigecho() { echo; echo "## $1"; echo; }
 
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"
}
 
vpnsetup() {
 
if ! grep -qs -e "release 6" -e "release 7" /etc/redhat-release; then
  exiterr "This script only supports CentOS/RHEL 6 and 7."
fi
 
if [ -f /proc/user_beancounters ]; then
  exiterr "OpenVZ VPS is not supported. Try OpenVPN: github.com/Nyr/openvpn-install"
fi
 
if [ "$(id -u)" != 0 ]; then
  exiterr "Script must be run as root. Try 'sudo sh $0'"
fi
 
net_iface=${VPN_NET_IFACE:-'eth0'}
def_iface="$(route 2>/dev/null | grep '^default' | grep -o '[^ ]*$')"
[ -z "$def_iface" ] && def_iface="$(ip -4 route list 0/0 2>/dev/null | grep -Po '(?<=dev )(\S+)')"
 
def_iface_state=$(cat "/sys/class/net/$def_iface/operstate" 2>/dev/null)
if [ -n "$def_iface_state" ] && [ "$def_iface_state" != "down" ]; then
  if ! grep -qs raspbian /etc/os-release; 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"
fi
 
net_iface_state=$(cat "/sys/class/net/$net_iface/operstate" 2>/dev/null)
if [ -z "$net_iface_state" ] || [ "$net_iface_state" = "down" ] || [ "$net_iface" = "lo" ]; then
  printf "Error: Network interface '%s' is not available.\n" "$net_iface" >&2
  if [ -z "$VPN_NET_IFACE" ]; then
cat 1>&2 <<EOF
Unable to detect the default network interface. Manually re-run this script with:
  sudo VPN_NET_IFACE="your_default_interface_name" sh "$0"
EOF
  fi
  exit 1
fi
 
[ -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 | head -c 16)"
  VPN_USER=vpnuser
  VPN_PASSWORD="$(LC_CTYPE=C tr -dc 'A-HJ-NPR-Za-km-z2-9' < /dev/urandom | 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
 
bigecho "VPN setup in progress... Please be patient."
 
# Create and change to working dir
mkdir -p /opt/src
cd /opt/src || exiterr "Cannot enter /opt/src."
 
bigecho "Installing packages required for setup..."
 
yum -y install wget bind-utils openssl \
  iproute gawk grep sed net-tools || exiterr2
 
bigecho "Trying to auto discover IP of this server..."
 
cat <<'EOF'
In case the script hangs here for more than a few minutes,
press Ctrl-C to abort. Then edit it and manually enter IP.
EOF
 
# In case auto IP discovery fails, enter server's public IP here.
PUBLIC_IP=${VPN_PUBLIC_IP:-''}
 
# Try to auto discover IP of this server
[ -z "$PUBLIC_IP" ] && PUBLIC_IP=$(dig @resolver1.opendns.com -t A -4 myip.opendns.com +short)
 
# Check IP for correct format
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. Edit the script and manually enter it."
 
bigecho "Adding the EPEL repository..."
 
epel_url="https://dl.fedoraproject.org/pub/epel/epel-release-latest-$(rpm -E '%{rhel}').noarch.rpm"
yum -y install epel-release || yum -y install "$epel_url" || exiterr2
 
bigecho "Installing packages required for the VPN..."
 
yum -y install nss-devel nspr-devel pkgconfig pam-devel \
  libcap-ng-devel libselinux-devel curl-devel \
  flex bison gcc make ppp xl2tpd || exiterr2
 
OPT1='--enablerepo=*server-optional*'
OPT2='--enablerepo=*releases-optional*'
if grep -qs "release 6" /etc/redhat-release; then
  yum -y remove libevent-devel
  yum "$OPT1" "$OPT2" -y install libevent2-devel fipscheck-devel || exiterr2
else
  yum -y install systemd-devel iptables-services || exiterr2
  yum "$OPT1" "$OPT2" -y install libevent-devel fipscheck-devel || exiterr2
fi
 
bigecho "Installing Fail2Ban to protect SSH..."
 
yum -y install fail2ban || exiterr2
 
bigecho "Compiling and installing Libreswan..."
 
SWAN_VER=3.22
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/$swan_file"
if ! { wget -t 3 -T 30 -nv -O "$swan_file" "$swan_url1" || wget -t 3 -T 30 -nv -O "$swan_file" "$swan_url2"; }; then
  exiterr "Cannot download Libreswan source."
fi
/bin/rm -rf "/opt/src/libreswan-$SWAN_VER"
tar xzf "$swan_file" && /bin/rm -f "$swan_file"
cd "libreswan-$SWAN_VER" || exiterr "Cannot enter Libreswan source dir."
[ "$SWAN_VER" = "3.22" ] && sed -i '/^#define LSWBUF_CANARY/s/-2$/((char) -2)/' include/lswlog.h
cat > Makefile.inc.local <<'EOF'
WERROR_CFLAGS =
USE_DNSSEC = false
EOF
NPROCS="$(grep -c ^processor /proc/cpuinfo)"
[ -z "$NPROCS" ] && NPROCS=1
make "-j$((NPROCS+1))" -s base && make -s install-base
 
# Verify the install and clean up
cd /opt/src || exiterr "Cannot enter /opt/src."
/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
 
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'}
 
# Create IPsec (Libreswan) 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
  protostack=netkey
  interfaces=%defaultroute
  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
  ike=3des-sha1,3des-sha2,aes-sha1,aes-sha1;modp1024,aes-sha2,aes-sha2;modp1024,aes256-sha2_512
  phase2alg=3des-sha1,3des-sha2,aes-sha1,aes-sha2,aes256-sha2_512
  sha2-truncbug=yes
 
conn l2tp-psk
  auto=add
  leftprotoport=17/1701
  rightprotoport=17/%any
  type=transport
  phase2=esp
  also=shared
 
conn xauth-psk
  auto=add
  leftsubnet=0.0.0.0/0
  rightaddresspool=$XAUTH_POOL
  modecfgdns1=$DNS_SRV1
  modecfgdns2=$DNS_SRV2
  leftxauthserver=yes
  rightxauthclient=yes
  leftmodecfgserver=yes
  rightmodecfgclient=yes
  modecfgpull=yes
  xauthby=file
  ike-frag=yes
  ikev2=never
  cisco-unity=yes
  also=shared
EOF
 
# 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
ms-dns $DNS_SRV1
ms-dns $DNS_SRV2
noccp
auth
mtu 1280
mru 1280
proxyarp
lcp-echo-failure 4
lcp-echo-interval 30
connect-delay 5000
EOF
 
# 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
 
bigecho "Updating sysctl settings..."
 
if ! grep -qs "hwdsl2 VPN script" /etc/sysctl.conf; then
  conf_bk "/etc/sysctl.conf"
  if [ "$(getconf LONG_BIT)" = "64" ]; then
    SHM_MAX=68719476736
    SHM_ALL=4294967296
  else
    SHM_MAX=4294967295
    SHM_ALL=268435456
  fi
cat >> /etc/sysctl.conf <<EOF
 
# Added by hwdsl2 VPN script
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = $SHM_MAX
kernel.shmall = $SHM_ALL
 
net.ipv4.ip_forward = 1
net.ipv4.conf.all.accept_source_route = 0
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_source_route = 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
 
bigecho "Updating IPTables rules..."
 
# Check if IPTables rules need updating
ipt_flag=0
IPT_FILE="/etc/sysconfig/iptables"
if ! grep -qs "hwdsl2 VPN script" "$IPT_FILE" \
   || ! iptables -t nat -C POSTROUTING -s "$L2TP_NET" -o "$net_iface" -j MASQUERADE 2>/dev/null \
   || ! iptables -t nat -C POSTROUTING -s "$XAUTH_NET" -o "$net_iface" -m policy --dir out --pol none -j MASQUERADE 2>/dev/null; then
  ipt_flag=1
fi
 
# Add IPTables rules for VPN
if [ "$ipt_flag" = "1" ]; then
  service fail2ban stop >/dev/null 2>&1
  iptables-save > "$IPT_FILE.old-$SYS_DT"
  iptables -I INPUT 1 -p udp --dport 1701 -m policy --dir in --pol none -j DROP
  iptables -I INPUT 2 -m conntrack --ctstate INVALID -j DROP
  iptables -I INPUT 3 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
  iptables -I INPUT 4 -p udp -m multiport --dports 500,4500 -j ACCEPT
  iptables -I INPUT 5 -p udp --dport 1701 -m policy --dir in --pol ipsec -j ACCEPT
  iptables -I INPUT 6 -p udp --dport 1701 -j DROP
  iptables -I FORWARD 1 -m conntrack --ctstate INVALID -j DROP
  iptables -I FORWARD 2 -i "$net_iface" -o ppp+ -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
  iptables -I FORWARD 3 -i ppp+ -o "$net_iface" -j ACCEPT
  iptables -I FORWARD 4 -i ppp+ -o ppp+ -s "$L2TP_NET" -d "$L2TP_NET" -j ACCEPT
  iptables -I FORWARD 5 -i "$net_iface" -d "$XAUTH_NET" -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
  iptables -I FORWARD 6 -s "$XAUTH_NET" -o "$net_iface" -j ACCEPT
  # Uncomment if you wish to disallow traffic between VPN clients themselves
  # iptables -I FORWARD 2 -i ppp+ -o ppp+ -s "$L2TP_NET" -d "$L2TP_NET" -j DROP
  # iptables -I FORWARD 3 -s "$XAUTH_NET" -d "$XAUTH_NET" -j DROP
  iptables -A FORWARD -j DROP
  iptables -t nat -I POSTROUTING -s "$XAUTH_NET" -o "$net_iface" -m policy --dir out --pol none -j MASQUERADE
  iptables -t nat -I POSTROUTING -s "$L2TP_NET" -o "$net_iface" -j MASQUERADE
  echo "# Modified by hwdsl2 VPN script" > "$IPT_FILE"
  iptables-save >> "$IPT_FILE"
fi
 
bigecho "Creating basic Fail2Ban rules..."
 
if [ ! -f /etc/fail2ban/jail.local ] ; then
cat > /etc/fail2ban/jail.local <<'EOF'
[ssh-iptables]
enabled  = true
filter   = sshd
action   = iptables[name=SSH, port=ssh, protocol=tcp]
logpath  = /var/log/secure
EOF
fi
 
bigecho "Enabling services on boot..."
 
if grep -qs "release 6" /etc/redhat-release; then
  chkconfig iptables on
  chkconfig fail2ban on
else
  systemctl --now mask firewalld 2>/dev/null
  systemctl enable iptables fail2ban 2>/dev/null
fi
if ! grep -qs "hwdsl2 VPN script" /etc/rc.local; then
  if [ -f /etc/rc.local ]; then
    conf_bk "/etc/rc.local"
  else
    echo '#!/bin/sh' > /etc/rc.local
  fi
cat >> /etc/rc.local <<'EOF'
 
# Added by hwdsl2 VPN script
(sleep 15
modprobe -q pppol2tp
service ipsec restart
service xl2tpd restart
echo 1 > /proc/sys/net/ipv4/ip_forward)&
EOF
fi
 
bigecho "Starting services..."
 
# Restore SELinux contexts
restorecon /etc/ipsec.d/*db 2>/dev/null
restorecon /usr/local/sbin -Rv 2>/dev/null
restorecon /usr/local/libexec/ipsec -Rv 2>/dev/null
 
# Reload sysctl.conf
sysctl -e -q -p
 
# Update file attributes
chmod +x /etc/rc.local
chmod 600 /etc/ipsec.secrets* /etc/ppp/chap-secrets* /etc/ipsec.d/passwd*
 
# Apply new IPTables rules
iptables-restore < "$IPT_FILE"
 
# Fix xl2tpd on CentOS 7, if kernel module "l2tp_ppp" is unavailable
if grep -qs "release 7" /etc/redhat-release; then
  if ! modprobe -q l2tp_ppp; then
    sed -i '/^ExecStartPre/s/^/#/' /usr/lib/systemd/system/xl2tpd.service
    systemctl daemon-reload
  fi
fi
 
# Restart services
modprobe -q pppol2tp
service fail2ban restart 2>/dev/null
service ipsec restart 2>/dev/null
service xl2tpd restart 2>/dev/null
 
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
 
================================================
 
EOF
 
}
 
## Defer setup until we have the complete script
vpnsetup "$@"
 
exit 0

5、安装完，会打印Server IP, IPseck PSK, Username, Password信息，我们可以换成自己配置的

//先修改PSK，将PSK后面的字符替换掉
    vim /etc/ipsec.secrets
 
// 修改用户名和密码 ，将用户名和密码修改为自已想要的字符
    vim /etc/ppp/chap-secrets
 
//重启IPsec和xl2tpd服务
    systemctl restart ipsec xl2tpd

6、现在可以尝试连接vpn了，连接方法如下：

　　win10 and win8

右键单击系统托盘中的无线/网络图标。
选择打开网络和共享中心。
点击设置一个新的连接或网络。
选择连接到工作区，然后单击下一步。
单击使用我的Internet连接（VPN）。
Your VPN Server IP在Internet地址栏中输入。
在目的地名称字段中输入任何你喜欢的，然后点击创建。
返回到网络和共享中心。在左侧，点击更改适配器设置。
右键单击新的VPN条目，然后选择“ 属性”。
单击安全选项卡。选择“使用IPsec的第2层隧道协议（L2TP / IPSec）”作为VPN的类型。
点击允许这些协议。一定要选择“挑战握手认证协议（CHAP）”复选框。
点击高级设置按钮。
选择使用预共享密钥进行验证，并输入Your VPN IPsec PSK的关键。
单击确定关闭高级设置。
单击确定以保存VPN连接详细信息。

　　win7，vista和xp

点击开始菜单并进入控制面板。
转到网络和Internet部分。
点击网络和共享中心。
点击设置一个新的连接或网络。
选择连接到工作区，然后单击下一步。
单击使用我的Internet连接（VPN）。
Your VPN Server IP在Internet地址栏中输入。
在目的地名称字段中输入任何你喜欢的东西。
检查现在不要连接; 只需设置它，以便以后可以连接复选框。
点击下一步。
Your VPN Username在用户名字段中输入。
Your VPN Password在密码字段中输入。
选中记住此密码复选框。
点击创建，然后关闭。
返回到网络和共享中心。在左侧，点击更改适配器设置。
右键单击新的VPN条目，然后选择“ 属性”。
单击选项选项卡，并取消选中包括Windows登录域。
单击安全选项卡。选择“使用IPsec的第2层隧道协议（L2TP / IPSec）”作为VPN的类型。
点击允许这些协议。一定要选择“挑战握手认证协议（CHAP）”复选框。
点击高级设置按钮。
选择使用预共享密钥进行验证，并输入Your VPN IPsec PSK的关键。
单击确定关闭高级设置。
单击确定以保存VPN连接详细信息。

　　注意：如果连接不上，需要更改注册表，点击查看详细

在cmd命令行执行
 
//对于Windows Vista，7，8.x和10
REG ADD HKLM\SYSTEM\CurrentControlSet\Services\PolicyAgent /v AssumeUDPEncapsulationContextOnSendRule /t REG_DWORD /d 0x2 /f
 
//仅适用于Windows XP
REG ADD HKLM\SYSTEM\CurrentControlSet\Services\IPSec /v AssumeUDPEncapsulationContextOnSendRule /t REG_DWORD /d 0x2 /f
 
//虽然不常见，但某些Windows系统禁用IPsec加密，导致连接失败。要重新启用它，请运行以下命令并重新启动您的PC
REG ADD HKLM\SYSTEM\CurrentControlSet\Services\RasMan\Parameters /v ProhibitIpSec /t REG_DWORD /d 0x0 /f

　　OS X

打开系统偏好设置并转到网络部分。
点击窗口左下角的+按钮。
从“ 接口”下拉菜单中选择“ VPN ” 。
从“ VPN类型”下拉菜单中选择“ IPSec上的L2TP”。
输入你喜欢的服务名称。
点击创建。
输入Your VPN Server IP的服务器地址。
输入Your VPN Username的帐户名称。
点击认证设置按钮。
在“ 用户验证”部分中，选择“ 密码”单选按钮并进入Your VPN Password。
在“ 机器验证”部分中，选择“ 共享机密”单选按钮并进入Your VPN IPsec PSK。
点击OK。
选中菜单栏中显示VPN状态复选框。
单击“ 高级”按钮，确保选中“ 发送所有通过VPN连接的通信”复选框。
单击“ TCP / IP”选项卡，并确保“ 配置IPv6”部分中的“ 仅限本地链接”。
单击确定关闭高级设置，然后单击应用以保存VPN连接信息。

　　Android

启动设置应用程序。
点击无线和网络部分中的更多...。
点击VPN。
点击添加VPN配置文件或屏幕右上方的+图标。
在名称字段中输入您喜欢的任何内容。
在类型下拉菜单中选择L2TP / IPSec PSK。
Your VPN Server IP在服务器地址栏中输入。
输入Your VPN IPsec PSK的预共享的IPSec密钥场。
点按保存。
点击新的VPN连接。
Your VPN Username在用户名字段中输入。
Your VPN Password在密码字段中输入。
选中保存帐户信息复选框。
点击连接。

　　ios

进入设置 - >常规 - > VPN。
点击添加VPN配置...。
点按类型。选择L2TP并返回。
点按“ 说明”，然后输入您喜欢
点击服务器并输入Your VPN Server IP。
点击帐户并输入Your VPN Username。
点击密码并输入Your VPN Password。
点击秘密并进入Your VPN IPsec PSK。
确保发送所有通信开关打开。
点按完成。
滑动VPN开关。

　　Linux

#####要设置VPN客户端，请首先安装以下软件包####
# Ubuntu & Debian
apt-get update
apt-get -y install strongswan xl2tpd
 
# CentOS & RHEL
yum -y install epel-release
yum -y install strongswan xl2tpd
 
# Fedora
yum -y install strongswan xl2tpd
 
#####创建VPN变量（用实际值替换）####
VPN_SERVER_IP='your_vpn_server_ip'
VPN_IPSEC_PSK='your_ipsec_pre_shared_key'
VPN_USER='your_vpn_username'
VPN_PASSWORD='your_vpn_password'
 
#####配置strongSwan#####
cat > /etc/ipsec.conf <<EOF
# ipsec.conf - strongSwan IPsec configuration file
 
# basic configuration
 
config setup
  # strictcrlpolicy=yes
  # uniqueids = no
 
# Add connections here.
 
# Sample VPN connections
 
conn %default
  ikelifetime=60m
  keylife=20m
  rekeymargin=3m
  keyingtries=1
  keyexchange=ikev1
  authby=secret
  ike=aes128-sha1-modp1024,3des-sha1-modp1024!
  esp=aes128-sha1-modp1024,3des-sha1-modp1024!
 
conn myvpn
  keyexchange=ikev1
  left=%defaultroute
  auto=add
  authby=secret
  type=transport
  leftprotoport=17/1701
  rightprotoport=17/1701
  right=$VPN_SERVER_IP
EOF
 
cat > /etc/ipsec.secrets <<EOF
: PSK "$VPN_IPSEC_PSK"
EOF
 
chmod 600 /etc/ipsec.secrets
 
# For CentOS/RHEL & Fedora ONLY
mv /etc/strongswan/ipsec.conf /etc/strongswan/ipsec.conf.old 2>/dev/null
mv /etc/strongswan/ipsec.secrets /etc/strongswan/ipsec.secrets.old 2>/dev/null
ln -s /etc/ipsec.conf /etc/strongswan/ipsec.conf
ln -s /etc/ipsec.secrets /etc/strongswan/ipsec.secrets
 
#####Configure xl2tpd#####
cat > /etc/xl2tpd/xl2tpd.conf <<EOF
[lac myvpn]
lns = $VPN_SERVER_IP
ppp debug = yes
pppoptfile = /etc/ppp/options.l2tpd.client
length bit = yes
EOF
 
cat > /etc/ppp/options.l2tpd.client <<EOF
ipcp-accept-local
ipcp-accept-remote
refuse-eap
require-chap
noccp
noauth
mtu 1280
mru 1280
noipdefault
defaultroute
usepeerdns
connect-delay 5000
name $VPN_USER
password $VPN_PASSWORD
EOF
 
chmod 600 /etc/ppp/options.l2tpd.client
 
VPN客户端设置现在完成。按照以下步骤进行连接。
 
注意：每次尝试连接到VPN时都必须重复以下所有步骤
###创建xl2tpd控制文件：###
mkdir -p /var/run/xl2tpd
touch /var/run/xl2tpd/l2tp-control
 
###重新启动服务###
service strongswan restart
service xl2tpd restart
 
###启动IPsec连接###
# Ubuntu & Debian
ipsec up myvpn
 
# CentOS/RHEL & Fedora
strongswan up myvpn
 
###启动L2TP连接###
echo "c myvpn" > /var/run/xl2tpd/l2tp-control
 
运行ifconfig并检查输出。你现在应该看到一个新的界面ppp0
 
检查您现有的默认路由
ip route
 
在输出中找到这一行：default via X.X.X.X ...。写下这个网关IP，用于下面的两个命令
从新的默认路由中排除您的VPN服务器的IP（用实际值替换）
route add YOUR_VPN_SERVER_IP gw X.X.X.X
 
如果您的VPN客户端是远程服务器，则还必须从新的默认路由中排除本地PC的公共IP，以防止您的SSH会话被断开（用实际值替换）：
route add YOUR_LOCAL_PC_PUBLIC_IP gw X.X.X.X
 
添加一个新的默认路由，以开始通过VPN服务器路由流量：
route add default dev ppp0
 
VPN连接现在完成。确认您的流量正在正确路由：
wget -qO- http://ipv4.icanhazip.com; echo
 
上述命令应该返回Your VPN Server IP
 
要通过VPN服务器停止路由流量
route del default dev ppp0
 
断开连接
# Ubuntu & Debian
echo "d myvpn" > /var/run/xl2tpd/l2tp-control
ipsec down myvpn
 
# CentOS/RHEL & Fedora
echo "d myvpn" > /var/run/xl2tpd/l2tp-control
strongswan down myvpn

7、这一个帐户明显不够用了，所以还是要找如何能多人共享方法，经过一阵折腾，终于找到方法了

1. 在 /etc/ppp/chap-secrets 中添加第二个用户，格式为： "username" l2tpd "password" * 
 
2. 执行 openssl passwd -1 "password" 得到一串MD5加密的字符串，如： $1$5NwpneO7$YD82DhVJxCQpQ4zahB1N01 
 
3. 复制这一段字符串到 /etc/ipsec.d/passwd 中，新行如下： username:$1$5NwpneO7$YD82DhVJxCQpQ4zahB1N01:xauth-psk ，红色是手工添加的。
 
4. systemctl restart ipsec xl2tpd

8、vpn使用的端口，注意开放

(注意是：udp):500， 4500， 1701

9、这个脚本安装vpn的时候会添加很多iptables的规则，然而我并没有用它的规则，因为进入文件/etc/sysconfig/iptables,把里面的内容删除了

，然后自己添加一条规则

iptables -t nat -A POSTROUTING -s 192.168.42.0/24 -o eth0 -j MASQUERADE

如果不添加这条规则，会导致客户端连接vpn 之后无法连接外网，加上后，客户单会通过vpn 服务器连接外网