前段时间下载了红帽的linux，版本为redhat 9.0，整整刻了三张CD。最初是为了体验一下linux下QQ聊天软件的功能，最后因内核太低（官方推荐内核在2.6以上，我下载的版本是2.4）而告终。最大的收获是了解了linux下文件系统及linux下软件与windows的不同，还有linux下ADSL的连接设置。
linux下局域网的连接很简单，在菜单的网络设置里，填好IP地址及子网掩码就OK了，ADSL的连接要费些周折了。前面的博文里介绍了如何设置windows下不用路由自动拨号上网的技巧，linux下也有相同点，就是要一步一步的输入上网信息，建立连接。不同点就是在linux要通过输入指令来完成ADSL的设置。
首先打开终端，在终端里输入adsl-setup ,根据提示，完成设置：
[root@localhost root]# adsl-setup
Welcome to the ADSL client setup. First, I will run some checks on
system to make sure the PPPoE client is installed properly…
LOGIN NAME
Enter your Login Name (default root): (username) ‘此处输入ADSL的用户名。
INTERFACE
Enter the Ethernet interface connected to the ADSL modem For
Solaris, this is likely to be something like /dev/hme0. For
Linux, it will be ethX, where ‘X’ is a number. (default eth0): ‘直接用默认的eth0就行了。
Do you want the link to come up on demand, or stay up continuously?
If you want it to come up on demand, enter the idle time in seconds
after which the link should be dropped. If you want the link to stay up
permanently, enter ‘no’ (two letters, lower-case.)
NOTE:
Demand-activated links do not interact well with dynamic IP addresses.
You may have some problems with demand-activated links.
Enter the demand value (default no): ‘输默认的NO
DNS
Please enter the IP address of your ISP’s primary DNS server.
If your ISP claims that ‘the server will provide dynamic DNS addresses’,
enter
‘server’ (all lower-case) here. ’DNS地址，南京地区的主DNS为218.2.135.1，辅DNS为61.147.37.1其它地区可参照
当地ISP
If you just press enter, I will assume you know what you are doing
and not modify your DNS setup.
Enter
the DNS information here: server
PASSWORD ‘输入ADSL密码，默认为自己的电话号码
Please enter your Password: ’再次输入密码
Please re-enter your Password:
USERCTRL
Please enter ‘yes’ (two letters, lower-case.) if you want to allow normal
user to start or stop DSL connection (default yes): y ‘是否允许普通用户开启或关闭ADSL连接，默认允许。
FIREWALLING
Please choose the firewall rules to use. Note that these rules are very
basic. You are strongly encouraged to use a more sophisticated firewall
setup; however, these will provide basic security. If you are
running any servers on your machine, you must choose ‘NONE’ and set up
firewalling yourself. Otherwise, the firewall rules will deny access
to all standard servers like Web, e-mail, ftp, etc. If you are
using SSH, the rules will block outgoing SSH connections which allocate
a privileged source port. ’选择防火墙的等级，0到2，按需要选。
The firewall choices are: 0 -
NONE: This script will not set any firewall rules. You are responsible for
ensuring the security of your machine. You are STRONGLY recommended
to use some kind of firewall rules. 1 -
STANDALONE: Appropriate for a basic stand-alone web-surfing
workstation 2 -
MASQUERADE: Appropriate for a machine acting as an Internet gateway
for a LAN
Choose a type of firewall (0-2): 0
Start this connection at boot time
Do you want to start this connection at boot time? ‘是否在启动时自动连接？
Please enter no or yes (default no):y
**
Summary of what you entered ** ’以下是ADSL账号设置信息
Ethernet
Interface: eth0
User name: nj007.cn
Activate-on-demand: No
DNS addresses: Supplied by ISP’s server
Firewalling: NONE
User Control: y
Accept these settings and adjust configuration files (y/n)? y ‘以上信息正确吗，Y保存，N重填。
Adjusting
/etc/sysconfig/network-scripts/ifcfg-ppp0
Adjusting
/etc/ppp/chap-secrets and /etc/ppp/pap-secrets
(But first backing it up to /etc/ppp/chap-secrets.bak)
(But first backing it up to /etc/ppp/pap-secrets.bak)
Congratulations, it should be all set up!
Type ‘/sbin/ifup ppp0′ to bring up your xDSL link and ‘/sbin/ifdown ppp0′
to bring it down.
Type ‘/sbin/adsl-status /etc/sysconfig/network-scripts/ifcfg-ppp0′ to see
the link status.
[root@localhost root]#
经过以上设置之后，连接ADSL的linux就能正常连接Internet了。其实如果自己想研究Linux，完全不用像我那样下载之后刻成光盘再一步一步的安装，因为我的电脑有两块硬盘，我是拿那块不常用的硬盘安装的。在只有一块硬盘的情况下可以选择用虚拟机来安装多系统。不推荐直接装双系统，因为那样会引起硬盘引导区的错误造成两个系统均不能正常启动。
像现在比较出名的linux系统有ubuntu（乌班图），redflag（中科红旗）等，做的都很优秀。尤其是在去年打击盗版期间，微软的XP销量并没有明显上升，linux的系统却深入人心。linux的开源性使得现在有越来越多的编程爱好者加入了linux的开发中，同时linux也成为微软最强悍的竞争对手。对于现在来说linux并没有普及，更多的用于服务器或是工作站中，相信再过不久linux会走向更多的用户电脑中。