參考 http://blog.changyy.org/2014/01/linux-vpn-server-pptpipsecl2tp-ubuntu.html , 但 ipsec.conf 設置檢查時會出 現 NAT-T 失敗 , 再參考 http://www.vmvps.com/ubuntu-1404-install-l2tp-ipsec-vpn-tutorial.html 有關 ipsec.conf 設 置,整合出此篇,留個記錄日後好查 1. 安裝需要的軟體 $ sudo apt-get install pptpd openswan xl2tpd ppp (pptpd 可不用,很多Switch已提供) 2.增加使用者帳/密資料,若有 pppoe 撥號密碼也會存於此檔 $ sudo vim /etc/ppp/chap-secrets # L2TP username l2tpd password * 其中 username, password 都是明碼 3. IPSEC/L2TP $ sudo su $ echo "net.ipv4.ip_forward = 1" | tee -a /etc/sysctl.conf $ echo "net.ipv4.conf.all.accept_redirects = 0" | tee -a /etc/sysctl.conf $ echo "net.ipv4.conf.all.send_redirects = 0" | tee -a /etc/sysctl.conf $ for vpn in /proc/sys/net/ipv4/conf/*; do echo 0 > $vpn/accept_redirects; echo 0 > $vpn/send_redirects; done $ sysctl -p $ sudo vim /etc/rc.local for vpn in /proc/sys/net/ipv4/conf/*; do echo 0 > $vpn/accept_redirects; echo 0 > $vpn/send_redire