0x01 安装

====> CentOS

RPM安装 下载：https://pkgs.org/download/strongswan
wget http://download-ib01.fedoraproject.org/pub/epel/7/x86_64/Packages/s/strongswan-5.7.2-1.el7.x86_64.rpm
rpm -ivh strongswan-*.rpm

或者是

yum -y install epel-release
yum -y install openssl-devel strongswan
查找相关插件 yum search swan
其它插件无需安装，尤其是strongswan-libipsec ，貌似与高于2.6的内核有冲突，导致无法连接服务器
libipsec用于创建ipsec0网卡和UDP封装，高版本使用kernel-netlink

====> Ubuntu

apt -y install openssl libssl-dev strongswan libstrongswan

0x02 服务器端

====> ipsec.conf

# EAP(Extensible Authentication Portocol) 可扩展身份认证协议
# IKE/ESP 密钥交换协议和数据验证加密
# right 是 remote 服务器端
# left 是 local 本地端

config setup
charondebug="cfg 2" # log 提议
uniqueids=never # 多个客户连接同一用户

conn %default
ike=aes128-sha256-ecp256,aes256-sha384-ecp384,aes128-sha256-modp2048,aes128-sha1-modp2048,aes256-sha384-modp4096,aes256-sha256-modp4096,aes256-sha1-modp4096,aes128-sha256-modp1536,aes128-sha1-modp1536,aes256-sha384-modp2048,aes256-sha256-modp2048,aes256-sha1-modp2048,aes128-sha256-modp1024,aes128-sha1-modp1024,aes256-sha384-modp1536,aes256-sha256-modp1536,aes256-sha1-modp1536,aes256-sha384-modp1024,aes256-sha256-modp1024,aes256-sha1-modp1024!
esp=aes128gcm16-ecp256,aes256gcm16-ecp384,aes128-sha256-ecp256,aes256-sha384-ecp384,aes128-sha256-modp2048,aes128-sha1-modp2048,aes256-sha384-modp4096,aes256-sha256-modp4096,aes256-sha1-modp4096,aes128-sha256-modp1536,aes128-sha1-modp1536,aes256-sha384-modp2048,aes256-sha256-modp2048,aes256-sha1-modp2048,aes128-sha256-modp1024,aes128-sha1-modp1024,aes256-sha384-modp1536,aes256-sha256-modp1536,aes256-sha1-modp1536,aes256-sha384-modp1024,aes256-sha256-modp1024,aes256-sha1-modp1024,aes128gcm16,aes256gcm16,aes128-sha256,aes128-sha1,aes256-sha384,aes256-sha256,aes256-sha1!
keyingtries=1

conn myvpn
keyexchange=ikev2
# ike=aes256-aes192-aes128-sha384-sha256-sha1-modp3072-modp2048-modp1536-modp1024!
# esp=aes256-aes192-aes128-sha384-sha256-sha1!
rekey=no
compress=no

left=%any
# leftid=%domain.ltd
# leftfirewall=no
leftupdown=/etc/strongswan/strongswan.d/proxyndp.updown
leftsubnet=0.0.0.0/0,::/0
leftauth=pubkey
leftsendcert=always
leftcert=server.cert.pem

right=%any
# rightid=%hostname
rightsourceip=10.10.2.1/24,2001:db8::/96
rightdns=8.8.8.8,8.8.4.4,2001:4860:4860::8888,2001:4860:4860::8844
rightsendcert=never
rightauth=eap-mschapv2

# tfc=%mtu
eap_identity=%any
dpdaction=clear
dpddelay=2400s
fragmentation=yes
auto=add

====> ipsec.secrets

# 取决于ipsec.conf 中的 leftauth的这两行之一
: RSA "私约加密密码"
: EAP "password"

====> 防火墙和路由转发

iptables -t nat -A POSTROUTING -s {IPv4}/24 -o eth0 -j MASQUERADE
ip6tables -t nat -A POSTROUTING -s {IPv6}/112 -o eth0 -j MASQUERADE

在 /etc/sysctl.conf 中追加如下三行

net.ipv4.ip_forward=1
net.ipv6.conf.all.forwarding=1
net.ipv6.conf.all.proxy_ndp=1

执行 sysctl -p

====> 启动/停止

ipsec/strongswan restart

0x03 客户端

====> ipsec.conf

# ipsec.conf - strongSwan IPsec configuration file
# basic configuration

config setup
# strictcrlpolicy=yes
uniqueids = never

# Add connections here.
conn client
keyexchange=ikev2
# ike=aes256-sha256-modp2048,3des-sha1-modp2048,aes256-sha1-modp2048!
# esp=aes256-sha256,3des-sha1,aes256-sha1!
right=pub.6tu.me
rightid=%pub.6tu.me
rightsubnet=0.0.0.0/0,::/0
rightauth=pubkey

leftsourceip=%config,%config6
# leftauth=eap-mschapv2
leftauth=eap
eap_identity=user
type=tunnel
auto=add

#配置LAN访问不走IPsec通道
conn exempt
right=127.0.0.1
leftsubnet=192.168.0.0/24
rightsubnet=192.168.0.0/24
type=passthrough
auto=route

====> ipsec.secrets

# 取决于ipsec.conf 中的 leftauth的这两行之一
: RSA "私约加密密码"
: EAP "password"

====> 防火墙和路由转发

用 ip -6 route 或者 ip route 查看当前路由
ip route 或者 ip route show table 220命令来查看

ip rule add from {IPv4}/24 table main prio 1
ip -6 rule add from {IPv6}/64 table main prio 1

====> 启动/停止

# systemctl restart network
ipsec/strongswan restart
ipsec/strongswan up/down ccc

0x04 其它事项

====> 证书认证(非必须)

yum/apt -y install ca-certificates

cp ca.pem /etc/pki/ca-trust/source/anchors/
cp ca.pem /etc/pki/tls/certs/

update-ca-trust extract

====> 参考资料

https://oogami.name/1467/
https://wiki.strongswan.org/projects/strongswan/wiki/IKEv2ClientConfig
https://libreswan.org/wiki/Subnet_to_subnet_VPN
https://wiki.strongswan.org/projects/strongswan/wiki/VirtualIp
Linux开源VPN之strongSwan
https://www.jianshu.com/p/ce6c545efd8a
https://www.cnblogs.com/Su-per-man/p/9952292.html
https://blog.csdn.net/puppylpg/article/details/64918562

0x05 注意事项

====> 配置选项

# leftauth=pubkey or eap, 取决于所选的网关配置
# leftcert=certificate, 仅当 leftauth=pubkey (e.g. peerCert.der)
# eap_identity=username, 仅当 leftauth=eap (e.g. peer)
# leftprotoport = 17/1701 需要注释掉
# rightprotoport = 17/%any 需要注释掉
type=passthrough
type=transport
auto=route

keyingtries=%forever
dpdaction=restart
closeaction=restart
====> 错误调试

启动后抛出如下错误，一般是内核不支持 IKE,隧道。尝试 modprobe af_key

no netkey IPsec stack detected
no KLIPS IPsec stack detected
no known IPsec stack detected, ignoring!

proxyndp.updown 脚本，在IPV6网络无效时使用

#!/bin/bash
IFACE=eth0 # configure me
ADDR=${PLUTO_PEER_CLIENT%/*}
case $PLUTO_VERB in
up-client-v6)
echo "Adding proxy NDP for $ADDR via $IFACE"
ip -6 neigh add proxy $ADDR dev $IFACE
;;
down-client-v6)
echo "Removing proxy NDP for $ADDR via $IFACE"
ip -6 neigh delete proxy $ADDR dev $IFACE
;;
up-client)
echo "Adding proxy ARP for $ADDR via $IFACE"
ip neigh add proxy $ADDR dev $IFACE
;;
down-client)
echo "Removing proxy ARP for $ADDR via $IFACE"
ip neigh delete proxy $ADDR dev $IFACE
;;
esac 2>&1 | logger -t proxyndp.updown

0x06 各个功能模块说明

charon :貌似管理 IKE(Internet Key Exchange) 守护进程

strongSwan IPsec client
charon-cmd charon-systemd

strongSwan IPsec client, pki 制作数字证书命令工具, SCEP(简单证书注册协议) client
strongswan-pki strongswan-scepclient

strongSwan IPsec client, swanctl command
strongswan-swanctl

IPsec VPN 主程序
strongswan

strongSwan 守护启动器和配置文件解析器
strongswan-starter

IKE（Internet Key Exchange） 守护进程
strongswan-charon strongswan-libcharon

strongSwan charon library
libcharon-standard-plugins libcharon-extra-plugins

strongSwan 实用和加密库
libstrongswan libstrongswan-standard-plugins libstrongswan-extra-plugins

网络管理框架插件 / 可与NetworkManager进行交互的插件
network-manager-strongswan strongswan-nm

TNC(Trusted Network Connect's ) 可信网络连接协议
IF-MAP(Interface for Metadata Access Point)
PDP(Packet Data Protoco)

base / client / server files
strongswan-tnc-base strongswan-tnc-client strongswan-tnc-server

TNC 的插件
strongswan-tnc-ifmap strongswan-tnc-pdp