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一、操作环境：
* Y1 Y- ~4 X0 H: X* @; ?( Z
/ D( ?7 P. u* R) n机器系统与配置：三台机器的关健部件
3 z8 a+ o8 J) L: u# y8 Z2 _第一台：台式机，双网卡，8139和8029，操作系统RedHat 8.0
0 W) I: Z, [% Z第二台：Toshiba notebook，PC卡。RTL-8139/8139C/8139C+，操作系统RedHat 8.0
) x, m  W! _0 w0 I/ p6 B5 [! `第三台：台式机,8029网卡，操作系统windowme
Hub[集线器]：Tp-Link 10M，8口
ADSL，乙太口，非路由。

' B/ D( |* t, E3 m+ B/ W1 C& T4 T二、网卡设置如下：
在第一台机器的双网卡的接法：把ADSL接在eth0上，把eth1接在HUB上。
第一块网卡的ip设置：
- s/ G' @% h$ I' o$ d: l' Rip地址:192.168.0.1
掩码:255.255.255.0
第二块网卡的设置
9 Z7 Z, G; D1 x$ ?# ?/ |# R. ~ip地址:192.168.0.2
掩码：255.255.255.0
在这两块网卡中，不要设置网关。
++++++++++++++++++++++++++++++++++++++++
! i/ w# ?) |( a, ~4 T% Z& b第二台：Toshiba notebook的网卡设置
- x9 b: J6 u' m0 g& T$ n" lIP：192.168.0.6
掩码：255.255.255.0
网关：192.168.0.1
DNS:设置电信给的，或者下面的也行
202.96.134.133
+ E8 F7 I8 |' o+ @1 n202.96.168.68
3 |/ \' p, P) [++++++++++++++++++++++++++++++++++++++++
% [) N6 F. p, _第三台机器的网卡设置
9 \1 d2 i9 c8 [P：192.168.0.8
掩码：255.255.255.0
网关：192.168.0.1
DNS:设置电信给的，或者下面的也行
202.96.134.133
202.96.168.68
0 m. {2 ]' s8 w% W& O) W( t2 R+ g三、设置ppp拔号，
1]删除原来的ppp的ADSL链接。
0 ~3 D% [0 Z$ m5 L/ N# ?8 S如果redhat-config-network原来已经用 redhat-config-network设置的ppp的ADSL连接拔号，用下面的命令调用删除。
#redhat-config-network

% Z! g: A) N+ n/ d0 T/ o2]在终端上以root权限运行
#adsl-setup
1 P0 D% R. v  ~" A
* Z: w2 R- v; v' \; R. k0 }
; T8 N# f! }8 J  c/ z[root@LinuxSir02 root]# adsl-setup
/ Q% [  ?6 I8 O3 O8 i
Welcome to the ADSL client setup. First, I will run some checks on
0 h5 a" v- ?: P# s! [; t9 @  q; Hyour system to make sure the PPPoE client is installed properly...


6 {- k7 n- v0 Q) P/ E) l5 f. wLOGIN NAME

0 P/ [) x( f4 F) @$ R5 lEnter your Login Name (default root): ADSL提供商给的用户名，写在这里
4 i; P  Q( \5 f2 |' h. ?
$ [/ l1 o. i: U0 B8 dINTERFACE
/ h; A; j( V  [9 f& }
7 E0 i1 R' I/ e9 r2 _8 P) hEnter the Ethernet interface connected to the ADSL modem
5 Z2 A  _6 l) x0 aFor Solaris, this is likely to be something like /dev/hme0.
7 N0 F( E9 {7 K/ C. k' g3 \For Linux, it will be ethX, where 'X' is a number.
8 q# C$ h3 ?8 k9 z- C(default eth0): eth0这是ADSL通过第一台机器的第一张网卡eth0提供上网
/ R! d& \. c" I2 @- W
9 j0 z2 k0 `; j7 p) j
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
5 O1 R! f# Q7 ^4 m4 O1 y$ @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):在这里按一下回车就行了。
9 R$ o+ G# m* |, R
DNS

Please enter the IP address of your ISP's primary DNS server.
& ]9 V9 O7 r) C6 z+ iIf your ISP claims that 'the server will provide dynamic DNS addresses',
6 C+ S2 `; C5 a1 |! \* f: q& Nenter 'server' (all lower-case) here.
If you just press enter, I will assume you know what you are
4 N8 c2 F! v, Adoing and not modify your DNS setup.
Enter the DNS information here: 202.96.134.133这是DSN，最好用你本地电信给的
5 a7 m: V6 y9 t$ |: {9 KPlease enter the IP address of your ISP's secondary DNS server.
1 x. P# ^% O7 OIf you just press enter, I will assume there is only one DNS server.
/ L& J7 o' [. `9 |. Y6 eEnter the secondary DNS server address here: 202.96.168.68这是第二个DNS，也是电信给的。

% Y7 V/ F- z( I. `- u% u  ~7 g  k& gPASSWORD

9 k% c' h# M  Y! [3 FPlease enter your Password:在这里把ADSL提供商给的密码写上
Please re-enter your Password:

: V/ I! ]% i" ~  i% BUSERCTRL

9 ^  D1 B; Q/ f0 ]( Y) [* jPlease enter 'yes' (two letters, lower-case.) if you want to allow
% F& y; H8 M- k- S7 i0 mnormal user to start or stop DSL connection (default yes): yes
% R% D1 r& {, H" g+ b0 D9 S
FIREWALLING
' D/ G! }0 \# v6 a+ K# U% s% O& `
( q) i8 R0 o5 U! z" Y* jPlease choose the firewall rules to use. Note that these rules are
) j: ^. _0 x5 p8 v4 |/ [very basic. You are strongly encouraged to use a more sophisticated
. h6 C# d0 |- `5 O% k% M. R* ofirewall setup; however, these will provide basic security. If you
$ R$ F7 Q7 E. |) ^' k# lare 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
) C& v2 \! T5 Y9 W# aare using SSH, the rules will block outgoing SSH connections which
allocate a privileged source port.

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.
' D6 O  V+ p8 ~8 ]/ x. b1 - STANDALONE: Appropriate for a basic stand-alone web-surfing workstation
6 {: ]! Z) |5 H4 |2 - MASQUERADE: Appropriate for a machine acting as an Internet gateway
$ |" a; s$ F  S1 W5 @4 L0 R% Cfor a LAN
3 q: U/ Q2 c; l" NChoose a type of firewall (0-2): 2
2 E3 |6 c) P) p$ g4 \8 |
' U& t6 [( ]% q% AStart this connection at boot time
) N/ R' ~* b7 i- Y5 ~
$ ~5 [7 f  l) Y+ @Do you want to start this connection at boot time?
9 N; w( ^% v* K% Y. A7 nPlease enter no or yes (default no):yes
5 C: O! ]! A/ u; l
5 w( W, F* U2 @5 ]5 c3 |7 W** Summary of what you entered **

3 f" \; b7 F* y( {, o* B  MEthernet Interface: eth0
2 K4 p4 Q' l! p7 x. eUser name: ADSL用户名
" v' y6 ^& v% r1 O. rActivate-on-demand: No
  d% ]& s6 r5 A4 C8 \Primary DNS: 202.96.134.133
Secondary DNS: 202.96.168.68
Firewalling: MASQUERADE
! Q  F) v% {  \0 S' O7 b9 iUser Control: yes
1 T, H  P% |3 Y- yAccept these settings and adjust configuration files (y/n)?y
2 j+ i3 D% \1 H$ Y2 l9 O$ `2 p

& Q! L* H+ x# _) S0 M5 Y三、在/etc/rc.d/rc.local中加入如下：

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -o ppp0 -j MASQUERADE
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9 r$ t6 z6 b2 ^! `四、重新启动机器。就OK了。这有多简单