使用GPRS模块拨号上网之前需要一直pppd和chat
首先配置内核中的ppp选项，
Makemenuconfig
Devicedirver--->Networkdevice
│ │*** CAIF transport drivers *** │ │
│ │ <*> PPP (point-to-point protocol) support │ │
│ │ [*] PPP multilink support (EXPERIMENTAL)│ │
│ │ [*] PPP filtering │ │
│ │ <*> PPP support for async serial ports│ │
│ │ <*> PPP support for sync tty ports│ │
│ │ <*> PPP Deflate compression │ │
│ │ <*> PPP BSD-Compress compression│ │
│ │ <*> PPP MPPE compression (encryption) (EXPERIMENTAL) │ │
│ │ <*> PPP over Ethernet (EXPERIMENTAL)
[guanlei@centos6GPRS]$tar-xzfppp-2.4.4.tar.gz
[guanlei@centos6GPRS]$ls
ppp-2.4.4ppp-2.4.4.tar.gz
[guanlei@centos6GPRS]$cdppp-2.4.4
[guanlei@centos6ppp-2.4.4]$ls
Changes-2.3configureFAQmodulespppdumpREADME.cbcpREADME.MPPEREADME.pppoescripts
chatcontribincludePLUGINSpppstatsREADME.eap-srpREADME.MSCHAP80README.pwfdSETUP
commonetc.ppplinuxpppdREADMEREADME.linuxREADME.MSCHAP81README.sol2solaris
[guanlei@centos6ppp-2.4.4]$./configure
ConfiguringforLinux
CreatingMakefiles.
Makefile<=linux/Makefile.top
pppd/Makefile<=pppd/Makefile.linux
pppstats/Makefile<=pppstats/Makefile.linux
chat/Makefile<=chat/Makefile.linux
pppdump/Makefile<=pppdump/Makefile.linux
pppd/plugins/Makefile<=pppd/plugins/Makefile.linux
pppd/plugins/rp-pppoe/Makefile<=pppd/plugins/rp-pppoe/Makefile.linux
pppd/plugins/radius/Makefile<=pppd/plugins/radius/Makefile.linux
pppd/plugins/pppoatm/Makefile<=pppd/plugins/pppoatm/Makefile.linux
[guanlei@centos6ppp-2.4.4]$ls
Changes-2.3contriblinuxpppdREADME.cbcpREADME.MSCHAP80README.sol2
chatetc.pppMakefilepppdumpREADME.eap-srpREADME.MSCHAP81scripts
commonFAQmodulespppstatsREADME.linuxREADME.pppoeSETUP
configureincludePLUGINSREADMEREADME.MPPEREADME.pwfdsolaris
[guanlei@centos6ppp-2.4.4]$cdchat/
[guanlei@centos6chat]$ls
chat.8chat.cMakefileMakefile.linuxMakefile.sol2
[guanlei@centos6chat]$vimchat.c
[guanlei@centos6chat]$vimMakefile
[guanlei@centos6chat]$cd../pppd
[guanlei@centos6pppd]$vimauth.c
[guanlei@centos6pppd]$vimMakefile
CC=/opt/buildroot-.08/arm920t/usr/bin/arm-linux-gcc#addbyguanlei.1.21
[guanlei@centos6ppp-2.4.4]$make
过程省略。。。。
[guanlei@centos6ppp-2.4.4]$cdchat/
[guanlei@centos6chat]$ls
hat.oMakefileMakefile.linuxMakefile.sol2
[guanlei@centos6chat]$filechat
chat:ELF32-bitLSBexecutable,ARM,version1(SYSV),dynamicallylinked(usessharedlibs),notstripped
[guanlei@centos6pppd]$filepppd
pppd:ELF32-bitLSBexecutable,ARM,version1(SYSV),dynamicallylinked(usessharedlibs),notstripped
把生成的pppd 和chat 下载到自己的s3c2440开发板上，放在/usr/sbin中
使用gprs上网的时候需要如下几个脚本
一：编写gprs脚本为PPP连接指定了连接使用的设备、使用的控制字符传输速率、指定了硬件加速、溢出控制等。
#/etc/ppp/peers/gprs
#Usage:root>pppdcallgprs
#setseriral
/dev/ttyS1
#setbaudrate
115200
#setflowdate
nocrtscts
#加上参数-v告诉chat命令将其所有的输出／入拷贝到系统记录里（通常是#/var/log/messages）。-t6指定了执行chat该命令的时间为6s。chat脚本的位置可以位##于/etc/目录下，也可以位于/var下，这个可以更加需要灵活设置。
connect'/usr/sbin/chat-v-f/etc/ppp/chat/gprs-connect-chat'
#setdebug,sendmessageto/var/log/messages
debug
#Tokeeppppdontheterminal
nodetach
#hide-password
#Acceptthepeer'sideaofourlocalIPaddress
ipcp-accept-local
#Acceptthepeer'sideaofits(remote)IPaddress
ipcp-accept-remote
#dialupconnetionasthedefaultroute
defaultroute
usepeerdns
Noipdefault
具体查看的话，man8pppd
二，CHAT脚本
一个简单的chat脚本有下面的结构：
""AT
OKATDTdialnumber
CONNECT""
1)MODEM期望空字符串。这句话的意思直接理解就是MODEM不管收到什么字符串，先发出字符串AT；
2)期望收到“OK”字符串，然后发送字符串“ATDTdialnumber”
3)如果收到“CONNECT”，就不再发送，认为数据链路已建立连接。
4)如果需要进行超时控制，就可以加入如下字段：
TIMEOUT10
5)如果要增加对特殊情况的处理，就加入下面字段：
ABORTBUSY
ABORTNOANSWER
ABORTRINGING
意思是：如果收到字符串“BUSY”、“NOANSWER”、“RINGING”就退出执行。
编写自己的chat脚本
>vigprs-connect-chat
#/etc/ppp/gprs-connect-chat
#Copyright(c)guanlei995318056@
#Thisissecondpartofthepppdialscript.Itwillperformtheconnection
#
ABORT'BUSY'
ABORT'NOANSWER'
ABORT'NOCARRIER'
ABORT'NODIALTONE'
ABORT'ERROR'
ABORT'\nRING\r\n\r\nRING\r'
TIMEOUT20
''\rAT
#setapn
OKAT+CGDCONT=1,"IP","cmnet"
#拨号上网
OKATDT*99***1#
SAY"+requestingdataconnection\n"
CONNECT''
SAY"+connected\n"
开始测试：
>:ifconfigeth0down
>:ifconfig
要程序一直在后台运行，如果在前台运行的话，没办法ping,不能测试到底能不能上网
>:pppdcallgprs&
>:+requestingdataconnection
+connected
Serialconnectionestablished.
usingchannel2
iUsinginterfaceppp0
Connect:ppp0<-->/dev/ttyS1
fconfsent[LCPConfReqid=0x1<asyncmap0x0><magic0xf9216d0><pcomp><accomp>]
rcvd[LCPConfReqid=0x1<asyncmap0xa0000><authpap>]
sent[LCPConfAckid=0x1<asyncmap0xa0000><authpap>]
rcvd[LCPConfRejid=0x1<magic0xf9216d0><pcomp><accomp>]
sent[LCPConfReqid=0x2<asyncmap0x0>]
rcvd[LCPConfAckid=0x2<asyncmap0x0>]
NosecretfoundforPAPlogin
sent[PAPAuthReqid=0x1user="guanlei"password=<hidden>]
rcvd[PAPAuthAckid=0x1"LoginOK"]
Remotemessage:LoginOK
PAPauthenticationsucceeded
sent[CCPConfReqid=0x1<deflate15><deflate(old#)15><bsdv115>]
sent[IPCPConfReqid=0x1<compressVJ0f01><addr0.0.0.0><ms-dns10.0.0.0><ms-dns30.0.0.0>]
rcvd[LCPProtRejid=0x280fd0101000f1a0478001804780015032f]
Protocol-Rejectfor'CompressionControlProtocol'(0x80fd)received
consent[IPCPConfReqid=0x1<compressVJ0f01><addr0.0.0.0><ms-dns10.0.0.0><ms-dns30.0.0.0>]
rcvd[IPCPConfReqid=0x1<addr192.200.1.21>]
sent[IPCPConfAckid=0x1<addr192.200.1.21>]
rcvd[IPCPConfRejid=0x1<compressVJ0f01>]
sent[IPCPConfReqid=0x2<addr0.0.0.0><ms-dns10.0.0.0><ms-dns30.0.0.0>]
rcvd[IPCPConfNakid=0x2<addr10.110.1.110><ms-dns1211.137.58.20><ms-dns3211.137.64.163>]
sent[IPCPConfReqid=0x3<addr10.110.1.110><ms-dns1211.137.58.20><ms-dns3211.137.64.163>]
rcvd[IPCPConfAckid=0x3<addr10.110.1.110><ms-dns1211.137.58.20><ms-dns3211.137.64.163>]
localIPaddress10.110.1.110
remoteIPaddress192.200.1.21
primaryDNSaddress211.137.58.20
secondaryDNSaddress211.137.64.163
>:ifconfig
ppp0Linkencap:Point-to-PointProtocol
inetaddr:10.110.1.110P-t-P:192.200.1.21Mask:255.255.255.255
UPPOINTOPOINTRUNNINGNOARPMULTICASTMTU:1500Metric:1
RXpackets:4errors:0dropped:0overruns:0frame:0
TXpackets:6errors:0dropped:0overruns:0carrier:0
collisions:0txqueuelen:3
RXbytes:64(64.0B)TXbytes:125(125.0B)
>:
(103.235.46.39):56databytes
64bytesfrom103.235.46.39:seq=0ttl=48time=555.719ms
64bytesfrom103.235.46.39:seq=1ttl=48time=273.481ms
---pingstatistics---
3packetstransmitted,2packetsreceived,33%packetloss
round-tripmin/avg/max=273.481/414.600/555.719ms
>:ifconfig
ppp0Linkencap:Point-to-PointProtocol
inetaddr:10.110.1.110P-t-P:192.200.1.21Mask:255.255.255.255
UPPOINTOPOINTRUNNINGNOARPMULTICASTMTU:1500Metric:1
RXpackets:10errors:0dropped:0overruns:0frame:0
TXpackets:12errors:0dropped:0overruns:0carrier:0
collisions:0txqueuelen:3
RXbytes:686(686.0B)TXbytes:557(557.0B)
