Modem拔号网络的速度慢，但在一些环境下还是很有用。如传真和点对点连接。下面这篇有关Modem设置的文章就是我在配置Fax服务器时记录下来。
在配置拔号网络前，请先用上面介绍的Minicom工具与Modem通信，确定Modem在Linux下能正常工作。Modem拔号采用PPP协议与远程的拔号服务器建立连接。在Debian系统下，有一个叫pppconfig配置可帮助我们快速配置pppd拔号网络。运行pppconfig，按向导一步下配置下去就可以了。配置完成保存后，在/etc/ppp/peers目录下会生成一个配置文件，默认是provider。用以下命令启动拔号连接：
debian:~# pon provider #如果你的连接名不是provider，请用你所起的连接名代替
用以下命令可查看连接日志：
debian:~# plog Aug 29 09:54:01 debian pppd[1708]: sent [IPCP ConfReq id=0x3 <addr 218.20.81.4> <ms-dns1 61.144.56.101> <ms-dns3 202.96.128.86>] Aug 29 09:54:01 debian pppd[1708]: rcvd [IPCP ConfAck id=0x3 <addr 218.20.81.4> <ms-dns1 61.144.56.101> <ms-dns3 202.96.128.86>] Aug 29 09:54:01 debian pppd[1708]: Cannot determine ethernet address for proxy A RP Aug 29 09:54:01 debian pppd[1708]: local IP address 218.20.81.4 Aug 29 09:54:01 debian pppd[1708]: remote IP address 218.20.64.62 Aug 29 09:54:01 debian pppd[1708]: primary DNS address 61.144.56.101 Aug 29 09:54:01 debian pppd[1708]: secondary DNS address 202.96.128.86 Aug 29 09:54:01 debian pppd[1708]: Script /etc/ppp/ip-up started (pid 1711) Aug 29 09:54:02 debian pppd[1708]: Script /etc/ppp/ip-up finished (pid 1711), status = 0x0
用以下命令关闭连接：
debian:~# poff
用以下命令显示连接状态信息：
debian:~# pppstats
IN PACK VJCOMP VJUNC VJERR | OUT PACK VJCOMP VJUNC NON-VJ
9532 145 0 0 0 | 97 5 0 0 5
另外一种方法是利用wvdial这个拔号工具实现Modem拔号上网。操作方法也很简单，先下载wvdial软件包：
debian:~# apt-get install wvdial
下载完软件后会自动运行wvdial的配置程序，要求输入电话号码、用户名和密码。配置程序会自动检测你的Modem并生成/etc/wvdial.conf文件。文件内容如下：
[Dialer Defaults] #默认的拔号设置，可设置多个Dialer Phone = 96169 Username = 1 Password = 1 New PPPD = yes Modem = /dev/ttyS0 Baud = 115200 Init1 = ATZ Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 ISDN = 0 Modem Type = Analog Modem
当然，我们也可手动运行wvdialconf这个配置程序，如：
debian:~# wvdialconf /etc/wvdial.conf Scanning your serial ports for a modem. ttyS0<*1>: ATQ0 V1 E1 -- OK ttyS0<*1>: ATQ0 V1 E1 Z -- OK ttyS0<*1>: ATQ0 V1 E1 S0=0 -- OK ttyS0<*1>: ATQ0 V1 E1 S0=0 &C1 -- OK ttyS0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 -- OK ttyS0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK ttyS0<*1>: Modem Identifier: ATI -- TP560 Data/Fax/Voice 56K Modem ttyS0<*1>: Speed 4800: AT -- OK ttyS0<*1>: Speed 9600: AT -- OK ttyS0<*1>: Speed 19200: AT -- OK ttyS0<*1>: Speed 38400: AT -- OK ttyS0<*1>: Speed 57600: AT -- OK ttyS0<*1>: Speed 115200: AT -- OK ttyS0<*1>: Max speed is 115200; that should be safe. ttyS0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK Found a modem on /dev/ttyS0. Modem configuration written to /etc/wvdial.conf. ttyS0<Info>: Speed 115200; init "ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0"
配置完成后，用wvdial命令启动拔号：
debian:~# wvdial #启动默认拔号器，如有多个拔号器，可用wvdial dialer格式指定 --> WvDial: Internet dialer version 1.53 --> Initializing modem. --> Sending: ATZ ATZ OK --> Sending: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 OK --> Modem initialized. --> Sending: ATDT96169 --> Waiting for carrier. ATDT96169 CONNECT 45333/V42BIS --> Carrier detected. Waiting for prompt. ********************************* * Quidway A8010 Internet Server * * welcome!! * ********************************* please input username: --> Looks like a login prompt. --> Sending: 1 --> Don't know what to do! Starting pppd and hoping for the best. --> Starting pppd at Tue Aug 30 11:11:39 2005 --> pid of pppd: 1858
出现以上信息说明pppd连接成功，用ifconfig可以查看到一个ppp0的连接。