在ARM-LINUX平台实现4G模块PPP拨号上网（串口/USB）
串口拨号解压ppp程序包，交叉编译
#tar -xzvf ppp-2.4.5.tar.gz
#cd ./ppp-2.4.5
#./config
#make CC=arm-linux-gcc
内核配置
Device Drivers —>Network device support—> <*> PPP (point-to-point protocol) support
ppp安装
将交叉编译好的pppd、chat应用复制到开发平台下的/usr/sbin/下。将ppp、chatscripts两个文件夹复制到开发平台下的/etc/目录下。
PPP配置
修改配置文件 /etc/ppp/peers/provider
#example configuration for a dialup connection authenticated with PAP or CHAP
#
# This is the default configuration used by pon(1) and poff(1).
# See the manual page pppd(8) for information on all the options.
# MUST CHANGE: replace myusername@realm with the PPP login name given to
# your by your provider.
# There should be a matching entry with the password in /etc/ppp/pap-secrets
# and/or /etc/ppp/chap-secrets.
#user "myusername@realm"
# Serial device to which the modem is connected.
# ttyname 串口端口，若非以”/“开头，则会自动补充”/dev/“
/dev/ttyS6
#/dev/ttyUSB2
#NO硬件流控
nocrtscts
# 前台运行
nodetach
# speed 串口波特率
# Speed of the serial line.
#115200
9600
#hide-password
remotename cmnet
ipparam cmnet
debug
user "cmnet"
0.0.0.0:0.0.0.0
local
lock
dump
# Assumes that your IP address is allocated dynamically by the ISP.
# 由ISP提供IP
noipdefault
# Try to get the name server addresses from the ISP.
usepeerdns
# Use this connection as the default route.
#defaultroute
# Makes pppd "dial again" when the connection is lost.
persist
# Do not ask the remote to authenticate.
noauth
修改拨号脚本 /etc/chatscripts/pap
#you can use this script unmodified to connect to sites which allow
# authentication via PAP, CHAP and similar protocols.
# This script can be shared among different pppd peer configurations.
# To use it, add something like this to your /etc/ppp/peers/ file:
#
# connect "/usr/sbin/chat -v -f /etc/chatscripts/pap -T PHONE-NUMBER"
# user YOUR-USERNAME-IN-PAP-SECRETS
# noauth
# Uncomment the following line to see the connect speed.
# It will be logged to stderr or to the file specified with the -r chat option.
#REPORT CONNECT
TIMEOUT 15
ABORT "BUSY"
ABORT "DELAYED"
ABORT "ERROR"
ABORT "NO DIALTONE"
ABORT "NO CARRIER"
TIMEOUT 40
'' AT
OK AT+CSQ
#s模块APN设置报错，默认接入CMNET，注释掉此命令
#OK AT+CGDCONT=1,"IP","CMNET"
OK ATDT*99#
CONNECT
修改pap权限
chmod +x /etc/chatscripts/pap
串口通信测试
打开两个终端
cat /dev/ttyS*
另一个终端发送AT命令
echo “AT” > /dev/ttyS*
可以cat到 AT OK，通信成功。若通信失败请用模块默认波特率。
串口拨号
pppd call provider &
# pppd call provider &
pppd options in effect:
debug # (from /etc/ppp/peers/provider)
nodetach # (from /etc/ppp/peers/provider)
persist # (from /etc/ppp/peers/provider)
dump # (from /etc/ppp/peers/provider)
noauth # (from /etc/ppp/peers/provider)
user cmnet # (from /etc/ppp/peers/provider)
remotename cmnet # (from /etc/ppp/peers/provider)
/dev/ttyUSB2 # (from /etc/ppp/peers/provider)
9600 # (from /etc/ppp/peers/provider)
lock # (from /etc/ppp/peers/provider)
connect /usr/sbin/chat -s -v -f /etc/chatscripts/pap # (from /etc/ppp/peers/provider)
nocrtscts # (from /etc/ppp/peers/provider)
local # (from /etc/ppp/peers/provider)
asyncmap 0 # (from /etc/ppp/options)
lcp-echo-failure 4 # (from /etc/ppp/options)
lcp-echo-interval 30 # (from /etc/ppp/options)
hide-password # (from /etc/ppp/options)
ipparam cmnet # (from /etc/ppp/peers/provider)
noipdefault # (from /etc/ppp/peers/provider)
usepeerdns # (from /etc/ppp/peers/provider)
: # (from /etc/ppp/peers/provider)
noipx # (from /etc/ppp/options)
timeout set to 15 seconds
abort on (BUSY)
abort on (DELAYED)
abort on (ERROR)
abort on (NO DIALTONE)
abort on (NO CARRIER)
timeout set to 40 seconds
send (AT^M)
expect (OK)
AT^M^M
OK
-- got it
send (AT+CSQ^M)
expect (OK)
^M
AT+CSQ^M^M
+CSQ: 25,99^M
OK
-- got it
send (ATDT*99#^M)
expect (CONNECT)
^M
ATDT*99#^M^M
CONNECT
-- got it
Script /usr/sbin/chat -s -v -f /etc/chatscripts/pap finished (pid 1448), status = 0x0
Serial connection established.
using channel 1
Using interface ppp0
Connect: ppp0 <--> /dev/ttyUSB2
sent
rcvd
No auth is possible
sent
rcvd
rcvd
sent
sent
sent
sent
rcvd
rcvd
rcvd
Protocol-Reject for 'Compression Control Protocol' (0x80fd) received
rcvd
sent
rcvd
sent
rcvd
sent
rcvd
localIP address 100.109.117.176
remote IP address 10.0.0.1
primary DNS address 211.136.17.107
secondary DNS address 211.136.20.203
Script /etc/ppp/ip-up started (pid 1453)
Script /etc/ppp/ip-up finished (pid 1453), status = 0x0
#ifconfig
# ifconfig
docker0 Link encap:EthernetHWaddr 02:42:28:F3:6C:11
inet addr:172.17.0.1Bcast:172.17.255.255Mask:255.255.0.0
UP BROADCAST MULTICASTMTU:1500Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B)TX bytes:0 (0.0 B)
eth0 Link encap:EthernetHWaddr FE:C4:84:AF:B7:CE
inet addr:192.168.0.2Bcast:192.168.0.255Mask:255.255.255.0
inet6 addr: fe80::fcc4:84ff:feaf:b7ce/64 Scope:Link
UP BROADCAST RUNNING MULTICASTMTU:1500Metric:1
RX packets:628 errors:0 dropped:0 overruns:0 frame:0
TX packets:466 errors:4 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:57929 (56.5 KiB)TX bytes:78074 (76.2 KiB)
Interrupt:117
lo Link encap:Local Loopback
inet addr:127.0.0.1Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNINGMTU:65536Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B)TX bytes:0 (0.0 B)
ppp0 Link encap:Point-to-Point Protocol
inet addr:100.109.117.176P-t-P:10.0.0.1Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICASTMTU:1500Metric:1
RX packets:4 errors:0 dropped:0 overruns:0 frame:0
TX packets:5 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:64 (64.0 B)TX bytes:97 (97.0 B)
可以看到ppp0网卡
添加路由
#route add default dev ppp0
联网测试
#ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 56 data bytes
64 bytes from 8.8.8.8: seq=0 ttl=50 time=44.137 ms
64 bytes from 8.8.8.8: seq=1 ttl=50 time=41.198 ms
64 bytes from 8.8.8.8: seq=2 ttl=50 time=47.619 ms
64 bytes from 8.8.8.8: seq=3 ttl=50 time=40.627 ms
64 bytes from 8.8.8.8: seq=4 ttl=50 time=46.058 ms
ping域名如果失败，请添加DNS
从/etc/ppp/resolv.conf可以查看到当前运营商的DNS“nameserver 211.136.17.107”，将DNS"nameserver 211.136.17.107 # ppp0"添加到/etc/resolv.conf.重新拨号，done。
USB拨号
查看4G模块
ls /dev/ttyUSB*
/dev/ttyUSB0/dev/ttyUSB1/dev/ttyUSB2/dev/ttyUSB3
可以看到模块驱动加载成功，枚举出4个ttyUSB设备，查看模块手册：
ttyUSB0 专用数据业务端口
ttyUSB1 GPS
ttyUSB2 AT指令端口
ttyUSB3 诊断口
修改配置文件 /etc/ppp/peers/provider
/dev/ttyS6
#/dev/ttyUSB2
修改为：
#/dev/ttyS6
/dev/ttyUSB2
拨号测试
拨号和网络配置部分同串口拨号一样。
如果ls /dev/ttyUSB*看不到设备，可以执行lsusb
# lsusb
Bus 002 Device 003: ID 2949:7401
Bus 002 Device 001: ID 1d6b:0002
Bus 004 Device 001: ID 1d6b:0001
查阅模块手册，VID和PID为2949:7401，可以看到已经识别到模块。
手动添加U转串驱动：
sudo echo 2949 7401 > /sys/bus/usb-serial/drivers/option1/new_id
此时重新ls /dev/ttyUSB*即可看到设备。如果设备重启，需要重新手动添加U转串驱动。
拨号
后续步骤跟串口拨号相同。
高大上，厉害 请教下出错重新拨号是怎么处理的 4G模块有的提供USB网卡的驱动，这和PPP拨号相比，有什么差异？ 用modemmanager比裸ppp方便和稳定 qsun 发表于 2020-11-18 05:27
用modemmanager比裸ppp方便和稳定
{:handshake:}等有时间研究一下 jim166783 发表于 2020-11-17 19:44
请教下出错重新拨号是怎么处理的
我们以前是定时监测那个网卡，发现没有，重新拨号，多次不成功后，重启系统，或者重启网卡
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