使用GPRS子產品撥号上網之前需要一直pppd和chat
首先配置核心中的ppp選項，
Make menuconfig
Device dirver --->Network device
│ │ *** 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)
[[email protected] GPRS]$ tar -xzf ppp-2.4.4.tar.gz
[[email protected] GPRS]$ ls
ppp-2.4.4 ppp-2.4.4.tar.gz
[[email protected] GPRS]$ cd ppp-2.4.4
[[email protected] ppp-2.4.4]$ ls
Changes-2.3 configure FAQ modules pppdump README.cbcp README.MPPE README.pppoe scripts
chat contrib include PLUGINS pppstats README.eap-srp README.MSCHAP80 README.pwfd SETUP
common etc.ppp linux pppd README README.linux README.MSCHAP81 README.sol2 solaris
[[email protected] ppp-2.4.4]$ ./configure
Configuring for Linux
Creating Makefiles.
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
[[email protected] ppp-2.4.4]$ ls
Changes-2.3 contrib linux pppd README.cbcp README.MSCHAP80 README.sol2
chat etc.ppp Makefile pppdump README.eap-srp README.MSCHAP81 scripts
common FAQ modules pppstats README.linux README.pppoe SETUP
configure include PLUGINS README README.MPPE README.pwfd solaris
[[email protected] ppp-2.4.4]$ cd chat/
[[email protected] chat]$ ls
chat.8 chat.c Makefile Makefile.linux Makefile.sol2
[[email protected] chat]$ vim chat.c
[[email protected] chat]$ vim Makefile
[[email protected] chat]$ cd ../pppd
[[email protected] pppd]$ vim auth.c
[[email protected] pppd]$ vim Makefile
CC =/opt/buildroot-2012.08/arm920t/usr/bin/arm-linux-gcc#add by guanlei 2016.1.21
[[email protected] ppp-2.4.4]$ make
過程省略。。。。
[[email protected] ppp-2.4.4]$ cd chat/
[[email protected] chat]$ ls
chat chat.8 chat.c chat.o Makefile Makefile.linux Makefile.sol2
[[email protected] chat]$ file chat
chat: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), not stripped
[[email protected] pppd]$ file pppd
pppd: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), not stripped
把生成的pppd 和chat 下載下傳到自己的s3c2440開發闆上，放在/usr/sbin中
使用gprs上網的時候需要如下幾個腳本
一：編寫gprs腳本為PPP連接配接指定了連接配接使用的裝置、使用的控制字元傳輸速率、指定了硬體加速、溢出控制等。
#/etc/ppp/peers/gprs
# Usage: root>pppd call gprs
#set seriral
/dev/ttyS1
# set baudrate
115200
# set flowdate
nocrtscts
#加上參數-v 告訴 chat指令将其所有的輸出／入拷貝到系統記錄裡（通常是 #/var/log/messages）。-t 6 指定了執行chat該指令的時間為6s。chat腳本的位置可以位##于/etc/目錄下，也可以位于/var下，這個可以更加需要靈活設定。
connect '/usr/sbin/chat -v -f /etc/ppp/chat/gprs-connect-chat'
#set debug ,send message to /var/log/messages
debug
#To keep pppd on the terminal
nodetach
#hide-password
# Accept the peer's idea of our local IP address
ipcp-accept-local
# Accept the peer's idea of its (remote) IP address
ipcp-accept-remote
#dial up connetion as the default route
defaultroute
usepeerdns
Noipdefault
具體檢視的話，man 8 pppd
二， CHAT腳本
一個簡單的chat腳本有下面的結構：
"" AT
OK ATDT dialnumber
CONNECT ""
1) MODEM期望空字元串。這句話的意思直接了解就是MODEM不管收到什麼字元串，先發出字元串AT；
2) 期望收到“OK”字元串，然後發送字元串“ATDT dialnumber”
3) 如果收到“CONNECT”，就不再發送，認為資料鍊路已建立連接配接。
4)如果需要進行逾時控制，就可以加入如下字段：
TIMEOUT 10
5)如果要增加對特殊情況的處理，就加入下面字段：
ABORT BUSY
ABORT NO ANSWER
ABORT RINGING
意思是：如果收到字元串“BUSY”、“NO ANSWER”、“RINGING”就退出執行。
編寫自己的chat腳本
>vi gprs-connect-chat
#/etc/ppp/gprs-connect-chat
#Copyright (c) 2016 guanlei [email protected]
# This is second part of the ppp dial script. It will perform the connection
#
ABORT 'BUSY'
ABORT 'NO ANSWER'
ABORT 'NO CARRIER'
ABORT 'NO DIALTONE'
ABORT 'ERROR'
ABORT '\nRING\r\n\r\nRING\r'
TIMEOUT 20
'' \rAT
#set apn
OK AT+CGDCONT=1,"IP","cmnet"
# 撥号上網
OK ATDT*99***1#
SAY " + requesting data connection\n"
CONNECT ''
SAY " + connected\n"
開始測試：
>: ifconfig eth0 down
>: ifconfig
要程式一直在背景運作，如果在前台運作的話，沒辦法ping,不能測試到底能不能上網
>: pppd call gprs &
>: + requesting data connection
+ connected
Serial connection established.
using channel 2
iUsing interface ppp0
Connect: ppp0 <--> /dev/ttyS1
fconfsent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0xf9216d0> <pcomp> <accomp>]
rcvd [LCP ConfReq id=0x1 <asyncmap 0xa0000> <auth pap>]
sent [LCP ConfAck id=0x1 <asyncmap 0xa0000> <auth pap>]
rcvd [LCP ConfRej id=0x1 <magic 0xf9216d0> <pcomp> <accomp>]
sent [LCP ConfReq id=0x2 <asyncmap 0x0>]
rcvd [LCP ConfAck id=0x2 <asyncmap 0x0>]
No secret found for PAP login
sent [PAP AuthReq id=0x1 user="guanlei" password=<hidden>]
rcvd [PAP AuthAck id=0x1 "Login OK"]
Remote message: Login OK
PAP authentication succeeded
sent [CCP ConfReq id=0x1 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns3 0.0.0.0>]
rcvd [LCP ProtRej id=0x2 80 fd 01 01 00 0f 1a 04 78 00 18 04 78 00 15 03 2f]
Protocol-Reject for 'Compression Control Protocol' (0x80fd) received
consent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns3 0.0.0.0>]
rcvd [IPCP ConfReq id=0x1 <addr 192.200.1.21>]
sent [IPCP ConfAck id=0x1 <addr 192.200.1.21>]
rcvd [IPCP ConfRej id=0x1 <compress VJ 0f 01>]
sent [IPCP ConfReq id=0x2 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns3 0.0.0.0>]
rcvd [IPCP ConfNak id=0x2 <addr 10.110.1.110> <ms-dns1 211.137.58.20> <ms-dns3 211.137.64.163>]
sent [IPCP ConfReq id=0x3 <addr 10.110.1.110> <ms-dns1 211.137.58.20> <ms-dns3 211.137.64.163>]
rcvd [IPCP ConfAck id=0x3 <addr 10.110.1.110> <ms-dns1 211.137.58.20> <ms-dns3 211.137.64.163>]
local IP address 10.110.1.110
remote IP address 192.200.1.21
primary DNS address 211.137.58.20
secondary DNS address 211.137.64.163
>: ifconfig
ppp0 Link encap:Point-to-Point Protocol
inet addr:10.110.1.110 P-t-P:192.200.1.21 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:4 errors:0 dropped:0 overruns:0 frame:0
TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:64 (64.0 B) TX bytes:125 (125.0 B)
>: ping www.baidu.com
PING www.baidu.com (103.235.46.39): 56 data bytes
64 bytes from 103.235.46.39: seq=0 ttl=48 time=555.719 ms
64 bytes from 103.235.46.39: seq=1 ttl=48 time=273.481 ms
--- www.baidu.com ping statistics ---
3 packets transmitted, 2 packets received, 33% packet loss
round-trip min/avg/max = 273.481/414.600/555.719 ms
>: ifconfig
ppp0 Link encap:Point-to-Point Protocol
inet addr:10.110.1.110 P-t-P:192.200.1.21 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:10 errors:0 dropped:0 overruns:0 frame:0
TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:686 (686.0 B) TX bytes:557 (557.0 B)