多台電腦通過ADSL同時上網，如果有路由，那就太簡單了。但是，如果沒路由只有交換機怎麼辦呢？一般有兩種方法。
1、用雙網卡（一個接內網，一個接外網）的機器裝代理服務器軟件（windows下有winGet等）來完成，但這種方法要兩塊網卡（浪費）,同時還要裝代理軟件（煩，而且還會被打盜版）。
2、通過共享拔號連接來解決，這種方法很簡單且不需要其它的軟件。
對於windows下的第二種方法的實現網上有很文章且很簡單，在此不作闡述。
下面就我在linux(在centOS4.4,rhel as 4,fc5下測試通過)下如何通過adsl拔號與共享上網作一個簡單的記錄，希望對新手有所幫助。
1、拔號上網
1.1拔號軟件
linux下的拔號軟件很多，但比較好的是rp-pppoe,一般linux系統會自帶拔號軟件，如果你沒裝，請自己到google去找一個來裝上。
1.2拔號設置
切換為root用戶,只有root才能配置。
$ su
Password:
# /sbin/adsl-setup
按提示設置用戶名、密碼、DNS、及其它相關信息，下面是我的參考配置:
Welcome to the ADSL client setup. First, I will run some checks on
your system to make sure the PPPoE client is installed properly...
The following DSL config was found on your system:
Device: Name:
ppp0 DSLppp0
Please enter the device if you want to configure the present DSL config
(default ppp0) or enter 'n' if you want to create a new one:
LOGIN NAME
Enter your Login Name (default xyn0699647):
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):
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):
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.
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:
PASSWORD
Please enter your Password:
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):
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.