CentOS 5.4 源代码安装Openswan 2.6.28

# uname -r
2.6.18-164.el5

一、下载openswan
从www.openswan.org官方网站下载当前最新版本2.6.28

# tar xzvf openswan-2.6.28.tar.gz
# cd openswan-2.6.28

二、安装依赖包
在openswan源码目录下查看README
There a few packages required for Openswan to compile:

1. libgmp + libgmp-devel headers.  (GNU Math Precision Library)

2. gawk, flex and bison (usually included in all distributions)

gawk, flex and bison几个比较容易安装，gawk系统已默认安装，flex和bison可用yum安装，libgmp有点麻烦。先是下载的gmp-5.0.1.tar.gz，但启动openswan服务时会报错(libgmp.so.10)，只好删了。后来在CentOS系统盘找到相应的RPM包.

# rpm -ivh gmp-4.1.4-10.el5.i386.rpm
Preparing...                ########################################### [100%]
        package gmp-4.1.4-10.el5.i386 is already installed

# rpm -ivh gmp-devel-4.1.4-10.el5.i386.rpm
Preparing...                ########################################### [100%]
    1gmp-devel              ########################################### [100%]

三、安装openswan

#make programs
#make install

安装成功后，在/etc/目录下生成ipsec.conf配置文件和ipsec.d目录，同时在/usr/local/sbin下生成ipsec可执行程序、在/etc/initl.d/目录下生成ipsec shell脚本

四、openswan基本操作

1. 查看当前openswan版本
# ipsec --version
Linux Openswan U2.6.28/K(no kernel code presently loaded)
See `ipsec --copyright' for copyright information.

2. ipsec服务
# service ipsec start

# service ipsec restart

# service ipsec stop

3.验证openswan是否正确安装
# ipsec verify

Checking your system to see if IPsec got installed and started correctly:
Version check and ipsec on-path                                 [OK]
Linux Openswan U2.6.28/K2.6.18-164.el5 (netkey)
Checking for IPsec support in kernel                            [OK]
Testing against enforced SElinux mode                           [FAILED]

  SElinux is running in 'enforced' mode.
  If you encounter network related SElinux errors, especially when using KLIPS,
  try disabling SElinux using:

  echo "0" > /selinux/enforce (or edit /etc/sysconfig/selinux)

NETKEY detected, testing for disabled ICMP send_redirects       [FAILED]

  Please disable /proc/sys/net/ipv4/conf/*/send_redirects
  or NETKEY will cause the sending of bogus ICMP redirects!

NETKEY detected, testing for disabled ICMP accept_redirects     [FAILED]

  Please disable /proc/sys/net/ipv4/conf/*/accept_redirects
  or NETKEY will accept bogus ICMP redirects!

Checking that pluto is running                                  [FAILED]
  whack: Pluto is not running (no "/var/run/pluto/pluto.ctl")
Two or more interfaces found, checking IP forwarding            [FAILED]
  whack: Pluto is not running (no "/var/run/pluto/pluto.ctl")
Checking for 'ip' command                                       [OK]
Checking for 'iptables' command                                 [OK]
Opportunistic Encryption Support                                [DISABLED]

(1)disabe SELINUX
# vim /etc/sysconfig/selinux
设置 SELINUX=disabled

# setenforce 0

(2)disable ICMP send_redirects和accept_redirects
可编写shell脚本将/proc/sys/net/ipv4/conf/*/send_redirects和/proc/sys/net/ipv4/conf/*/accept_redirects disable掉

(3)enable ip_forward
# vim /etc/sysctl.conf
修改net.ipv4.ip_forward = 0 ->  net.ipv4.ip_forward = 1

# sysctl -p

4. 配置文件
(1)配置文件 (/etc/ipsec.conf)
查看ipsec.conf配置帮助 
# man 5 ipsec.conf

(2)密钥配置文件(/etc/ipsec.secrest)
查看ipsec.secrets配置帮助
# man 5 ipsec.secrets