centos6一键部署L2TP及解决方案

至于为什么需要搭建L2TP服务，这个大家都懂。先说一下为什么不用PPTP去科学上网，我用VPS搭建了一套shadowsocks + PPTP的服务。shadowsocks 主要是用在电脑端科学上网的。由于ios上没办法用shadowsocks，所以搭建了PPTP 服务。

shadowsock for ios 是收费的。如果想不收费的话，要么越狱，要么想其他办法。当然android不收费可以随便用。

起初一切正常，速度都还挺满意。后来朋友也需要这种特殊服务 ,那我就提供啦！但是发现，在他的办公环境下，没办法用公司网络通过PPTP 去科学上网。怎么办呢？搭建一个L2TP 服务，用的是这位大大的DearTanker’s 一键安装。步骤应该是这样的：

#每行我用'>'去区分，注意粘贴> wget --no-check-certificate https://raw.githubusercontent.com/teddysun/across/master/l2tp.sh> chmod +x l2tp.sh> ./l2tp.sh

然后你要做的就是稍等！片刻后就大功告成！
当然如果有遇到这种错误的，也不要着急！

iptables: Setting chains to policy ACCEPT: nat filter      [  OK  ]iptables: Flushing firewall rules:                         [  OK  ]iptables: Unloading modules:                               [  OK  ]iptables: Applying firewall rules:                         [  OK  ]ipsec_setup: Openswan IPsec apparently already active, start abortedStarting xl2tpd: Please wait a moment...Checking your system to see if IPsec got installed and started correctly:Version check and ipsec on-path                                 [OK]Linux Openswan U2.6.24/K2.6.32-573.8.1.el6.i686 (netkey)Checking for IPsec support in kernel                            [OK]Hardware RNG detected, testing if used properly                 [FAILED]Hardware RNG detected, testing if used properly [FAILED] Hardware RNG is present but 'rngd' or 'clrngd' is not running.No harware random used!NETKEY detected, testing for disabled ICMP send_redirects       [OK]NETKEY detected, testing for disabled ICMP accept_redirects     [OK]Checking for RSA private key (/etc/ipsec.secrets)               [OK]Checking that pluto is running                                  [OK]Pluto listening for IKE on udp 500                              [OK]Pluto listening for NAT-T on udp 4500                           [OK]Checking for 'ip' command                                       [OK]Checking for 'iptables' command                                 [OK]Opportunistic Encryption Support                                [DISABLED]

执行下面的shell去修复：

#每行我用'>'去区分，注意粘贴> yum install rng-tools> vim /etc/sysconfig/rngd> EXTRAOPTIONS="-r /dev/urandom"> chkconfig rngd on> service rngd restart

好了之后，去验证一下：

#每行我用'>'去区分，注意粘贴> ipsec setup restart> xl2tpd -D> ipsec verify

至此，完成。