Link1

https://expats-in-china.com/t/setup-a-vpn-ipsec-on-centos-7-using-strongswan/27

Link2

https://www.vultr.com/docs/using-strongswan-for-ipsec-vpn-on-centos-7

Link3

http://blog.leanote.com/post/shazi/Untitled-552ba6ca38f4117de8000169-5

New links

https://raymii.org/s/tutorials/IPSEC_vpn_with_CentOS_7.html

iptables -t nat -A POSTROUTING -j MASQUERADE
iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
iptables -A INPUT -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -p udp --dport 443 -j ACCEPT
iptables -A INPUT -m state --state NEW -m tcp -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -m state --state NEW -m udp -p udp --dport 443 -j ACCEPT
iptables -t nat -A POSTROUTING -s 20.30.0.0/24 -o eth0 -j MASQUERADE
iptables -A FORWARD -s 20.30.0.0/24 -j ACCEPT
iptables -A INPUT -i eth0 -m state --state NEW -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -i eth0 -m state --state NEW -p udp --dport 443 -j ACCEPT
service iptables save
service iptables restart
service iptables stop
service iptables start

http://www.rmalekghasemi.ir/file/dinstar.zip

http://forum.persianadmins.ir/threads/39177-%D8%AA%D8%BA%DB%8C%DB%8C%D8%B1-%D9%BE%D8%B3%D9%88%D8%B1%D8%AF-IBSng-%D8%AF%D8%B1-%D9%84%DB%8C%D9%86%D9%88%DA%A9%D8%B3

http://www.linuxlinks.com/article/20110420162039800/WebCaches.html

https://thornelabs.net/2015/03/29/setup-varnish-4-on-centos-6-as-a-caching-server-and-load-balancer.html

Real Time Interactive IP LAN Monitoring with IPTraf Tool

http://www.rmalekghasemi.ir/file/sambaserver.pdf

http://probind.org

Test, for example:

dig nl.alpinelinux.org @10.0.0.1

or:

nslookup www.google.cz 10.0.0.1

or use drill:

drill www.bbc.co.uk @10.0.0.1