Step 1 — 安装Installing StrongSwan
apt update
apt install strongswan strongswan-pki libcharon-extra-plugins libcharon-extauth-plugins libstrongswan-extra-plugins
Step 2 — 准备https证书 a Certificate Authority
/etc/ipsec.d/cacerts/Digicert-OV-DV-root.cer
/etc/ipsec.d/private/moneyslow.com.key
/etc/ipsec.d/certs/moneyslow.com.pem
Step 3 — 配置 Configuring StrongSwan ，就一个文件,注意文件格式，标准对齐的，不然载入报错。
#cat /etc/ipsec.conf
config setup
charondebug="ike 1, knl 1, cfg 0"
uniqueids=no
conn ikev2-vpn
auto=add
compress=no
type=tunnel
keyexchange=ikev2
fragmentation=yes
forceencaps=yes
dpdaction=clear
dpddelay=300s
rekey=no
left=%any
leftid=@
leftcert=/etc/ipsec.d/certs/moneyslow.com.pem
leftsendcert=always
leftsubnet=0.0.0.0/0
right=%any
rightid=%any
rightauth=eap-mschapv2
rightsourceip=10.10.10.0/24
rightdns=8.8.8.8,8.8.4.4
rightsendcert=never
eap_identity=%identity
ike=chacha20poly1305-sha512-curve25519-prfsha512,aes256gcm16-sha384-prfsha384-ecp384,aes256-sha1-modp1024,aes128-sha1-modp1024,3des-sha1-modp1024!
esp=chacha20poly1305-sha512,aes256gcm16-ecp384,aes256-sha256,aes256-sha1,3des-sha1!
Step 4 — 配置密码 Configuring Authentication
root@us:~# cat /etc/ipsec.secrets
: RSA /etc/ipsec.d/private/moneyslow.com.key
myname : EAP "mypassword"
重启服务，确认状态
root@us:~# systemctl restart strongswan-starter
root@us:~# systemctl status strongswan-starter
● strongswan-starter.service - strongSwan IPsec IKEv1/IKEv2 daemon using ipsec.conf
Loaded: loaded (/lib/systemd/system/strongswan-starter.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2023-08-17 02:04:18 UTC; 9s ago
............
Step 5 — 配置防火墙和内核ip转发 Configuring the Firewall & Kernel IP Forwarding
ufw allow OpenSSH
ufw enable
ufw allow 500,4500/udp
root@us:~# ip route show default
default via 200.200.200.1 dev eth0 proto dhcp src 200.200.200.55 metric 100
这里确认网卡的名称是eth0
this result shows the interface named eth0
配置防火墙规则
root@us:~# cat /etc/ufw/before.rules
#
# rules.before
#
# Rules that should be run before the ufw command line added rules. Custom
# rules should be added to one of these chains:
# ufw-before-input
# ufw-before-output
# ufw-before-forward
#
*nat
-A POSTROUTING -s 10.10.10.0/24 -o eth0 -m policy --pol ipsec --dir out -j ACCEPT
-A POSTROUTING -s 10.10.10.0/24 -o eth0 -j MASQUERADE
COMMIT
*mangle
-A FORWARD --match policy --pol ipsec --dir in -s 10.10.10.0/24 -o eth0 -p tcp -m tcp --tcp-flags SYN,RST SYN -m tcpmss --mss 1361:1536 -j TCPMSS --set-mss 1360
COMMIT
# Don't delete these required lines, otherwise there will be errors
*filter
:ufw-before-input - [0:0]
:ufw-before-output - [0:0]
:ufw-before-forward - [0:0]
:ufw-not-local - [0:0]
# End required lines
-A ufw-before-forward --match policy --pol ipsec --dir in --proto esp -s 10.10.10.0/24 -j ACCEPT
-A ufw-before-forward --match policy --pol ipsec --dir out --proto esp -d 10.10.10.0/24 -j ACCEPT
# allow all on loopback
-A ufw-before-input -i lo -j ACCEPT
-A ufw-before-output -o lo -j ACCEPT
# quickly process packets for which we already have a connection
-A ufw-before-input -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A ufw-before-output -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A ufw-before-forward -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
# drop INVALID packets (logs these in loglevel medium and higher)
-A ufw-before-input -m conntrack --ctstate INVALID -j ufw-logging-deny
-A ufw-before-input -m conntrack --ctstate INVALID -j DROP
# ok icmp codes for INPUT
-A ufw-before-input -p icmp --icmp-type destination-unreachable -j ACCEPT
-A ufw-before-input -p icmp --icmp-type time-exceeded -j ACCEPT
-A ufw-before-input -p icmp --icmp-type parameter-problem -j ACCEPT
-A ufw-before-input -p icmp --icmp-type echo-request -j ACCEPT
# ok icmp code for FORWARD
-A ufw-before-forward -p icmp --icmp-type destination-unreachable -j ACCEPT
-A ufw-before-forward -p icmp --icmp-type time-exceeded -j ACCEPT
-A ufw-before-forward -p icmp --icmp-type parameter-problem -j ACCEPT
-A ufw-before-forward -p icmp --icmp-type echo-request -j ACCEPT
# allow dhcp client to work
-A ufw-before-input -p udp --sport 67 --dport 68 -j ACCEPT
#
# ufw-not-local
#
-A ufw-before-input -j ufw-not-local
# if LOCAL, RETURN
-A ufw-not-local -m addrtype --dst-type LOCAL -j RETURN
# if MULTICAST, RETURN
-A ufw-not-local -m addrtype --dst-type MULTICAST -j RETURN
# if BROADCAST, RETURN
-A ufw-not-local -m addrtype --dst-type BROADCAST -j RETURN
# all other non-local packets are dropped
-A ufw-not-local -m limit --limit 3/min --limit-burst 10 -j ufw-logging-deny
-A ufw-not-local -j DROP
# allow MULTICAST mDNS for service discovery (be sure the MULTICAST line above
# is uncommented)
-A ufw-before-input -p udp -d 224.0.0.251 --dport 5353 -j ACCEPT
# allow MULTICAST UPnP for service discovery (be sure the MULTICAST line above
# is uncommented)
-A ufw-before-input -p udp -d 239.255.255.250 --dport 1900 -j ACCEPT
# don't delete the 'COMMIT' line or these rules won't be processed
COMMIT
配置内核参数
root@us:~# cat /etc/ufw/sysctl.conf
net/ipv4/conf/all/accept_redirects=0
net/ipv4/conf/default/accept_redirects=0
net/ipv6/conf/all/accept_redirects=0
net/ipv6/conf/default/accept_redirects=0
# Ignore bogus ICMP errors
net/ipv4/icmp_echo_ignore_broadcasts=1
net/ipv4/icmp_ignore_bogus_error_responses=1
net/ipv4/icmp_echo_ignore_all=0
# Don't log Martian Packets (impossible addresses)
# packets
net/ipv4/conf/all/log_martians=0
net/ipv4/conf/default/log_martians=0
#net/ipv4/tcp_fin_timeout=30
#net/ipv4/tcp_keepalive_intvl=1800
# Uncomment this to turn off ipv6 autoconfiguration
#net/ipv6/conf/default/autoconf=1
#net/ipv6/conf/all/autoconf=1
# Uncomment this to enable ipv6 privacy addressing
#net/ipv6/conf/default/use_tempaddr=2
#net/ipv6/conf/all/use_tempaddr=2
net/ipv4/ip_forward=1
net/ipv4/conf/all/accept_redirects=0
net/ipv4/conf/all/send_redirects=0
net/ipv4/ip_no_pmtu_disc=1
重新载入防火墙规则生效：
ufw disable
ufw enable
查看防火墙规则：
root@us:~# ufw status numbered
Status: active
To Action From
-- ------ ----
[ 1] OpenSSH ALLOW IN Anywhere
[ 2] 500,4500/udp ALLOW IN Anywhere
[ 3] OpenSSH (v6) ALLOW IN Anywhere (v6)
[ 4] 500,4500/udp (v6) ALLOW IN Anywhere (v6)
客户端的各种配置参考文章：