arm环境下，wpa_supplicant交叉编译+wifi sta连接详解

1、前言

wpa_supplicant 是一个用于 WiFi 客户端的加密认证工具，支持 WEP、WPA、WPA2 等多种加密方式。它通常与 wpa_cli 配合使用，用于管理 WiFi 连接。本文讲解wpa_supplicant 交叉编译全过程以及开发板使用wpa_supplican和udhcpc连接wifi全过程详解。

2、前期准备

虚拟机：ubuntu18.04

源码：

libnl-3.11.0.tar.gz

openssl-1.0.2u.tar.gz

wpa_supplicant-2.10.tar.gz

代码以及配置文件都已经上传到我的gitee

wpa_supplicent: wpa_supplicent交叉编译

3、源码编译

在所有源码目录下建一个文件夹，命名pkgconfig

后续将libnl和opssl编译生成的pkg文件都复制到这个目录下，这是为了wpa_supplicant编译时更好找到libnl和opssl的头文件和库

1、libopssl编译

./config  no-asm shared --prefix=$PWD/_install --cross-compile-prefix=arm-gcc7.3-linux-musleabi-
make CC=arm-gcc7.3-linux-musleabi-gcc
make install

需要注意的是如果编译报错:unrecognized command line option '-m64'

直接编辑Makefile，把-m64选项删除即可

将install目录下生成的lib/pkg目录下的.pc文件都复制到上面建的pkgconfig目录下

2、libnl编译

./configure --host=arm-gcc7.3-linux-musleabi --prefix=$PWD/_install
make install

编译完了，同理，将 .pc文件都复制到上面建的pkgconfig目录下

3、wpa_supplicant编译

wpa_supplicant源码的默认配置里有很多是不需要的，可以做一些裁剪，当然也可以用他的默认配置

使用默认配置：

cp defconfig .config

裁剪后的配置文件.config

# Example wpa_supplicant build time configuration
#
# This file lists the configuration options that are used when building the
# hostapd binary. All lines starting with # are ignored. Configuration option
# lines must be commented out complete, if they are not to be included, i.e.,
# just setting VARIABLE=n is not disabling that variable.
#
# This file is included in Makefile, so variables like CFLAGS and LIBS can also
# be modified from here. In most cases, these lines should use += in order not
# to override previous values of the variables.
 
BOARD_WIFI_VENDOR=realtek
 
# Uncomment following two lines and fix the paths if you have installed OpenSSL
# or GnuTLS in non-default location
#CFLAGS += -I/usr/local/openssl/include
#LIBS += -L/usr/local/openssl/lib
 
# Some Red Hat versions seem to include kerberos header files from OpenSSL, but
# the kerberos files are not in the default include path. Following line can be
# used to fix build issues on such systems (krb5.h not found).
#CFLAGS += -I/usr/include/kerberos
 
# Driver interface for generic Linux wireless extensions
# Note: WEXT is deprecated in the current Linux kernel version and no new
# functionality is added to it. nl80211-based interface is the new
# replacement for WEXT and its use allows wpa_supplicant to properly control
# the driver to improve existing functionality like roaming and to support new
# functionality.
#CONFIG_DRIVER_WEXT=y
 
# Driver interface for Linux drivers using the nl80211 kernel interface
CONFIG_DRIVER_NL80211=y
 
# QCA vendor extensions to nl80211
#CONFIG_DRIVER_NL80211_QCA=y
 
# driver_nl80211.c requires libnl. If you are compiling it yourself
# you may need to point hostapd to your version of libnl.
#
#CFLAGS += -I$<path to libnl include files>
#LIBS += -L$<path to libnl library files>
 
# Use libnl v2.0 (or 3.0) libraries.
#CONFIG_LIBNL20=y
 
# Use libnl 3.2 libraries (if this is selected, CONFIG_LIBNL20 is ignored)
#CONFIG_LIBNL32=y
 
 
# Driver interface for FreeBSD net80211 layer (e.g., Atheros driver)
#CONFIG_DRIVER_BSD=y
#CFLAGS += -I/usr/local/include
#LIBS += -L/usr/local/lib
#LIBS_p += -L/usr/local/lib
#LIBS_c += -L/usr/local/lib
 
# Driver interface for Windows NDIS
#CONFIG_DRIVER_NDIS=y
#CFLAGS += -I/usr/include/w32api/ddk
#LIBS += -L/usr/local/lib
# For native build using mingw
#CONFIG_NATIVE_WINDOWS=y
# Additional directories for cross-compilation on Linux host for mingw target
#CFLAGS += -I/opt/mingw/mingw32/include/ddk
#LIBS += -L/opt/mingw/mingw32/lib
#CC=mingw32-gcc
# By default, driver_ndis uses WinPcap for low-level operations. This can be
# replaced with the following option which replaces WinPcap calls with NDISUIO.
# However, this requires that WZC is disabled (net stop wzcsvc) before starting
# wpa_supplicant.
# CONFIG_USE_NDISUIO=y
 
# Driver interface for wired Ethernet drivers
#CONFIG_DRIVER_WIRED=y
 
# Driver interface for the Broadcom RoboSwitch family
#CONFIG_DRIVER_ROBOSWITCH=y
 
# Driver interface for no driver (e.g., WPS ER only)
#CONFIG_DRIVER_NONE=y
 
# Solaris libraries
#LIBS += -lsocket -ldlpi -lnsl
#LIBS_c += -lsocket
 
# Enable IEEE 802.1X Supplicant (automatically included if any EAP method is
# included)
CONFIG_IEEE8021X_EAPOL=y
 
# EAP-MD5
CONFIG_EAP_MD5=y
 
# EAP-MSCHAPv2
CONFIG_EAP_MSCHAPV2=y
 
# EAP-TLS
CONFIG_EAP_TLS=y
 
# EAL-PEAP
CONFIG_EAP_PEAP=y
 
# EAP-TTLS
CONFIG_EAP_TTLS=y
 
# EAP-FAST
# Note: If OpenSSL is used as the TLS library, OpenSSL 1.0 or newer is needed
# for EAP-FAST support. Older OpenSSL releases would need to be patched, e.g.,
# with openssl-0.9.8x-tls-extensions.patch, to add the needed functions.
# CONFIG_EAP_FAST=y
 
# EAP-GTC
CONFIG_EAP_GTC=y
 
# EAP-OTP
CONFIG_EAP_OTP=y
 
# EAP-SIM (enable CONFIG_PCSC, if EAP-SIM is used)
# CONFIG_EAP_SIM=y
 
# EAP-PSK (experimental; this is _not_ needed for WPA-PSK)
#CONFIG_EAP_PSK=y
 
# EAP-pwd (secure authentication using only a password)
#CONFIG_EAP_PWD=y
 
# EAP-PAX
#CONFIG_EAP_PAX=y
 
# LEAP
CONFIG_EAP_LEAP=y
 
# EAP-AKA (enable CONFIG_PCSC, if EAP-AKA is used)
# CONFIG_EAP_AKA=y
 
# EAP-AKA' (enable CONFIG_PCSC, if EAP-AKA' is used).
# This requires CONFIG_EAP_AKA to be enabled, too.
# CONFIG_EAP_AKA_PRIME=y
 
# Enable USIM simulator (Milenage) for EAP-AKA
#CONFIG_USIM_SIMULATOR=y
 
# EAP-SAKE
#CONFIG_EAP_SAKE=y
 
# EAP-GPSK
#CONFIG_EAP_GPSK=y
# Include support for optional SHA256 cipher suite in EAP-GPSK
#CONFIG_EAP_GPSK_SHA256=y
 
# EAP-TNC and related Trusted Network Connect support (experimental)
#CONFIG_EAP_TNC=y
 
# Wi-Fi Protected Setup (WPS)
# CONFIG_WPS=y
# Enable WPS external registrar functionality
# CONFIG_WPS_ER=y
# Disable credentials for an open network by default when acting as a WPS
# registrar.
#CONFIG_WPS_REG_DISABLE_OPEN=y
# Enable WPS support with NFC config method
# CONFIG_WPS_NFC=y
 
# EAP-IKEv2
#CONFIG_EAP_IKEV2=y
 
# EAP-EKE
#CONFIG_EAP_EKE=y
 
# PKCS#12 (PFX) support (used to read private key and certificate file from
# a file that usually has extension .p12 or .pfx)
CONFIG_PKCS12=y
 
# Smartcard support (i.e., private key on a smartcard), e.g., with openssl
# engine.
CONFIG_SMARTCARD=y
 
# PC/SC interface for smartcards (USIM, GSM SIM)
# Enable this if EAP-SIM or EAP-AKA is included
#CONFIG_PCSC=y
 
# Support HT overrides (disable HT/HT40, mask MCS rates, etc.)
#CONFIG_HT_OVERRIDES=y
 
# Support VHT overrides (disable VHT, mask MCS rates, etc.)
#CONFIG_VHT_OVERRIDES=y
 
# Development testing
#CONFIG_EAPOL_TEST=y
 
# Select control interface backend for external programs, e.g, wpa_cli:
# unix = UNIX domain sockets (default for Linux/*BSD)
# udp = UDP sockets using localhost (127.0.0.1)
# udp6 = UDP IPv6 sockets using localhost (::1)
# named_pipe = Windows Named Pipe (default for Windows)
# udp-remote = UDP sockets with remote access (only for tests systems/purpose)
# udp6-remote = UDP IPv6 sockets with remote access (only for tests purpose)
# y = use default (backwards compatibility)
# If this option is commented out, control interface is not included in the
# build.
CONFIG_CTRL_IFACE=y
# Include support for GNU Readline and History Libraries in wpa_cli.
# When building a wpa_cli binary for distribution, please note that these
# libraries are licensed under GPL and as such, BSD license may not apply for
# the resulting binary.
#CONFIG_READLINE=y
# Include internal line edit mode in wpa_cli. This can be used as a replacement
# for GNU Readline to provide limited command line editing and history support.
# CONFIG_WPA_CLI_EDIT=y
# Remove debugging code that is printing out debug message to stdout.
# This can be used to reduce the size of the wpa_supplicant considerably
# if debugging code is not needed. The size reduction can be around 35%
# (e.g., 90 kB).
#CONFIG_NO_STDOUT_DEBUG=y
# Remove WPA support, e.g., for wired-only IEEE 802.1X supplicant, to save
# 35-50 kB in code size.
#CONFIG_NO_WPA=y
# Remove IEEE 802.11i/WPA-Personal ASCII passphrase support
# This option can be used to reduce code size by removing support for
# converting ASCII passphrases into PSK. If this functionality is removed, the
# PSK can only be configured as the 64-octet hexstring (e.g., from
# wpa_passphrase). This saves about 0.5 kB in code size.
#CONFIG_NO_WPA_PASSPHRASE=y
# Disable scan result processing (ap_mode=1) to save code size by about 1 kB.
# This can be used if ap_scan=1 mode is never enabled.
#CONFIG_NO_SCAN_PROCESSING=y
# Select configuration backend:
# file = text file (e.g., wpa_supplicant.conf; note: the configuration file
#	path is given on command line, not here; this option is just used to
#	select the backend that allows configuration files to be used)
# winreg = Windows registry (see win_example.reg for an example)
CONFIG_BACKEND=file
# Remove configuration write functionality (i.e., to allow the configuration
# file to be updated based on runtime configuration changes). The runtime
# configuration can still be changed, the changes are just not going to be
# persistent over restarts. This option can be used to reduce code size by
# about 3.5 kB.
#CONFIG_NO_CONFIG_WRITE=y
# Remove support for configuration blobs to reduce code size by about 1.5 kB.
#CONFIG_NO_CONFIG_BLOBS=y
# Select program entry point implementation:
# main = UNIX/POSIX like main() function (default)
# main_winsvc = Windows service (read parameters from registry)
# main_none = Very basic example (development use only)
#CONFIG_MAIN=main
# Select wrapper for operating system and C library specific functions
# unix = UNIX/POSIX like systems (default)
# win32 = Windows systems
# none = Empty template
# CONFIG_OS=unix
# Select event loop implementation
# eloop = select() loop (default)
# eloop_win = Windows events and WaitForMultipleObject() loop
# CONFIG_ELOOP=eloop
# Should we use poll instead of select? Select is used by default.
#CONFIG_ELOOP_POLL=y
# Should we use epoll instead of select? Select is used by default.
#CONFIG_ELOOP_EPOLL=y
# Should we use kqueue instead of select? Select is used by default.
#CONFIG_ELOOP_KQUEUE=y
# Select layer 2 packet implementation
# linux = Linux packet socket (default)
# pcap = libpcap/libdnet/WinPcap
# freebsd = FreeBSD libpcap
# winpcap = WinPcap with receive thread
# ndis = Windows NDISUIO (note: requires CONFIG_USE_NDISUIO=y)
# none = Empty template
# CONFIG_L2_PACKET=linux
# Disable Linux packet socket workaround applicable for station interface
# in a bridge for EAPOL frames. This should be uncommented only if the kernel
# is known to not have the regression issue in packet socket behavior with
# bridge interfaces (commit 'bridge: respect RFC2863 operational state')').
#CONFIG_NO_LINUX_PACKET_SOCKET_WAR=y
# PeerKey handshake for Station to Station Link (IEEE 802.11e DLS)
CONFIG_PEERKEY=y
# IEEE 802.11w (management frame protection), also known as PMF
# Driver support is also needed for IEEE 802.11w.
# CONFIG_IEEE80211W=y
# Select TLS implementation
# openssl = OpenSSL (default)
# gnutls = GnuTLS
# internal = Internal TLSv1 implementation (experimental)
# none = Empty template
CONFIG_TLS=internal
# TLS-based EAP methods require at least TLS v1.0. Newer version of TLS (v1.1)
# can be enabled to get a stronger construction of messages when block ciphers
# are used. It should be noted that some existing TLS v1.0 -based
# implementation may not be compatible with TLS v1.1 message (ClientHello is
# sent prior to negotiating which version will be used)
#CONFIG_TLSV11=y
# TLS-based EAP methods require at least TLS v1.0. Newer version of TLS (v1.2)
# can be enabled to enable use of stronger crypto algorithms. It should be
# noted that some existing TLS v1.0 -based implementation may not be compatible
# with TLS v1.2 message (ClientHello is sent prior to negotiating which version
# will be used)
#CONFIG_TLSV12=y
# If CONFIG_TLS=internal is used, additional library and include paths are
# needed for LibTomMath. Alternatively, an integrated, minimal version of
# LibTomMath can be used. See beginning of libtommath.c for details on benefits
# and drawbacks of this option.
CONFIG_INTERNAL_LIBTOMMATH=y
#ifndef CONFIG_INTERNAL_LIBTOMMATH
#LTM_PATH=/usr/src/libtommath-0.39
#CFLAGS += -I$(LTM_PATH)
#LIBS += -L$(LTM_PATH)
#LIBS_p += -L$(LTM_PATH)
#endif
# At the cost of about 4 kB of additional binary size, the internal LibTomMath
# can be configured to include faster routines for exptmod, sqr, and div to
# speed up DH and RSA calculation considerably
#CONFIG_INTERNAL_LIBTOMMATH_FAST=y
# Include NDIS event processing through WMI into wpa_supplicant/wpasvc.
# This is only for Windows builds and requires WMI-related header files and
# WbemUuid.Lib from Platform SDK even when building with MinGW.
#CONFIG_NDIS_EVENTS_INTEGRATED=y
#PLATFORMSDKLIB="/opt/Program Files/Microsoft Platform SDK/Lib"
# Add support for old DBus control interface
# (fi.epitest.hostap.WPASupplicant)
#CONFIG_CTRL_IFACE_DBUS=y
# Add support for new DBus control interface
# (fi.w1.hostap.wpa_supplicant1)
#CONFIG_CTRL_IFACE_DBUS_NEW=y
# Add introspection support for new DBus control interface
#CONFIG_CTRL_IFACE_DBUS_INTRO=y
# Add support for loading EAP methods dynamically as shared libraries.
# When this option is enabled, each EAP method can be either included
# statically (CONFIG_EAP_<method>=y) or dynamically (CONFIG_EAP_<method>=dyn).
# Dynamic EAP methods are build as shared objects (eap_*.so) and they need to
# be loaded in the beginning of the wpa_supplicant configuration file
# (see load_dynamic_eap parameter in the example file) before being used in
# the network blocks.
#
# Note that some shared parts of EAP methods are included in the main program
# and in order to be able to use dynamic EAP methods using these parts, the
# main program must have been build with the EAP method enabled (=y or =dyn).
# This means that EAP-TLS/PEAP/TTLS/FAST cannot be added as dynamic libraries
# unless at least one of them was included in the main build to force inclusion
# of the shared code. Similarly, at least one of EAP-SIM/AKA must be included
# in the main build to be able to load these methods dynamically.
#
# Please also note that using dynamic libraries will increase the total binary
# size. Thus, it may not be the best option for targets that have limited
# amount of memory/flash.
#CONFIG_DYNAMIC_EAP_METHODS=y
# IEEE Std 802.11r-2008 (Fast BSS Transition)
# CONFIG_IEEE80211R=y
# Add support for writing debug log to a file (/tmp/wpa_supplicant-log-#.txt)
# CONFIG_DEBUG_FILE=y
# Send debug messages to syslog instead of stdout
#CONFIG_DEBUG_SYSLOG=y
# Set syslog facility for debug messages
#CONFIG_DEBUG_SYSLOG_FACILITY=LOG_DAEMON
# Add support for sending all debug messages (regardless of debug verbosity)
# to the Linux kernel tracing facility. This helps debug the entire stack by
# making it easy to record everything happening from the driver up into the
# same file, e.g., using trace-cmd.
#CONFIG_DEBUG_LINUX_TRACING=y
# Add support for writing debug log to Android logcat instead of standard
# output
# CONFIG_ANDROID_LOG=y
# Enable privilege separation (see README 'Privilege separation' for details)
#CONFIG_PRIVSEP=y
# Enable mitigation against certain attacks against TKIP by delaying Michael
# MIC error reports by a random amount of time between 0 and 60 seconds
#CONFIG_DELAYED_MIC_ERROR_REPORT=y
# Enable tracing code for developer debugging
# This tracks use of memory allocations and other registrations and reports
# incorrect use with a backtrace of call (or allocation) location.
#CONFIG_WPA_TRACE=y
# For BSD, uncomment these.
#LIBS += -lexecinfo
#LIBS_p += -lexecinfo
#LIBS_c += -lexecinfo
# Use libbfd to get more details for developer debugging
# This enables use of libbfd to get more detailed symbols for the backtraces
# generated by CONFIG_WPA_TRACE=y.
#CONFIG_WPA_TRACE_BFD=y
# For BSD, uncomment these.
#LIBS += -lbfd -liberty -lz
#LIBS_p += -lbfd -liberty -lz
#LIBS_c += -lbfd -liberty -lz
# wpa_supplicant depends on strong random number generation being available
# from the operating system. os_get_random() function is used to fetch random
# data when needed, e.g., for key generation. On Linux and BSD systems, this
# works by reading /dev/urandom. It should be noted that the OS entropy pool
# needs to be properly initialized before wpa_supplicant is started. This is
# important especially on embedded devices that do not have a hardware random
# number generator and may by default start up with minimal entropy available
# for random number generation.
#
# As a safety net, wpa_supplicant is by default trying to internally collect
# additional entropy for generating random data to mix in with the data fetched
# from the OS. This by itself is not considered to be very strong, but it may
# help in cases where the system pool is not initialized properly. However, it
# is very strongly recommended that the system pool is initialized with enough
# entropy either by using hardware assisted random number generator or by
# storing state over device reboots.
#
# wpa_supplicant can be configured to maintain its own entropy store over
# restarts to enhance random number generation. This is not perfect, but it is
# much more secure than using the same sequence of random numbers after every
# reboot. This can be enabled with -e<entropy file> command line option. The
# specified file needs to be readable and writable by wpa_supplicant.
#
# If the os_get_random() is known to provide strong random data (e.g., on
# Linux/BSD, the board in question is known to have reliable source of random
# data from /dev/urandom), the internal wpa_supplicant random pool can be
# disabled. This will save some in binary size and CPU use. However, this
# should only be considered for builds that are known to be used on devices
# that meet the requirements described above.
#CONFIG_NO_RANDOM_POOL=y
# IEEE 802.11n (High Throughput) support (mainly for AP mode)
CONFIG_IEEE80211N=y
# IEEE 802.11ac (Very High Throughput) support (mainly for AP mode)
# (depends on CONFIG_IEEE80211N)
#CONFIG_IEEE80211AC=y
# Wireless Network Management (IEEE Std 802.11v-2011)
# Note: This is experimental and not complete implementation.
# CONFIG_WNM=y
# Interworking (IEEE 802.11u)
# This can be used to enable functionality to improve interworking with
# external networks (GAS/ANQP to learn more about the networks and network
# selection based on available credentials).
# CONFIG_INTERWORKING=y
# Hotspot 2.0
# CONFIG_HS20=y
# Enable interface matching in wpa_supplicant
#CONFIG_MATCH_IFACE=y
# Disable roaming in wpa_supplicant
# CONFIG_NO_ROAMING=y
# AP mode operations with wpa_supplicant
# This can be used for controlling AP mode operations with wpa_supplicant. It
# should be noted that this is mainly aimed at simple cases like
# WPA2-Personal while more complex configurations like WPA2-Enterprise with an
# external RADIUS server can be supported with hostapd.
# CONFIG_AP=y
# P2P (Wi-Fi Direct)
# This can be used to enable P2P support in wpa_supplicant. See README-P2P for
# more information on P2P operations.
# CONFIG_P2P=y
# Enable TDLS support
# CONFIG_TDLS=y
# Wi-Fi Direct
# This can be used to enable Wi-Fi Direct extensions for P2P using an external
# program to control the additional information exchanges in the messages.
# CONFIG_WIFI_DISPLAY=y
# Autoscan
# This can be used to enable automatic scan support in wpa_supplicant.
# See wpa_supplicant.conf for more information on autoscan usage.
#
# Enabling directly a module will enable autoscan support.
# For exponential module:
#CONFIG_AUTOSCAN_EXPONENTIAL=y
# For periodic module:
#CONFIG_AUTOSCAN_PERIODIC=y
# Password (and passphrase, etc.) backend for external storage
# These optional mechanisms can be used to add support for storing passwords
# and other secrets in external (to wpa_supplicant) location. This allows, for
# example, operating system specific key storage to be used
#
# External password backend for testing purposes (developer use)
#CONFIG_EXT_PASSWORD_TEST=y
# Enable Fast Session Transfer (FST)
#CONFIG_FST=y
# Enable CLI commands for FST testing
#CONFIG_FST_TEST=y
# OS X builds. This is only for building eapol_test.
#CONFIG_OSX=y
# Automatic Channel Selection
# This will allow wpa_supplicant to pick the channel automatically when channel
# is set to "0".
#
# TODO: Extend parser to be able to parse "channel=acs_survey" as an alternative
# to "channel=0". This would enable us to eventually add other ACS algorithms in
# similar way.
#
# Automatic selection is currently only done through initialization, later on
# we hope to do background checks to keep us moving to more ideal channels as
# time goes by. ACS is currently only supported through the nl80211 driver and
# your driver must have survey dump capability that is filled by the driver
# during scanning.
#
# TODO: In analogy to hostapd be able to customize the ACS survey algorithm with
# a newly to create wpa_supplicant.conf variable acs_num_scans.
#
# Supported ACS drivers:
# * ath9k
# * ath5k
# * ath10k
#
# For more details refer to:
# http://wireless.kernel.org/en/users/Documentation/acs
#CONFIG_ACS=y
# Support Multi Band Operation
#CONFIG_MBO=y
#CONFIG_MESH=y

好了之后设置一下pkg文件的环境变量

export PKG_CONFIG_PATH=/share/test/wpa/pkgconfig/:$PKG_CONFIG_PATH

# /share/test/wpa/pkgconfig 一开始建的pkgconfig文件夹

然后

make CC=arm-gcc7.3-linux-musleabi-gcc

如果有报错找不到-lnl和-lnl-genl-3，就在.config文件中添加libnl的install路径

CFLAGS += -I/share/test/wpa/libnl-3.11.0/_install/include/libnl3/
LIBS += -L/share/test/wpa/libnl-3.11.0/_install/lib

# /share/test/wpa/libnl-3.11.0/_install libnl库install路径

4、arm环境使用

整体步骤：

1、安装wifi驱动

2、ifconfig wlan0 up

3、/opt/ipnc/wpa_supplicant -B -iwlan0 -c /opt/ipnc/wpa_supplicant.conf

4、udhcpc -i wlan0

注意点：

其中wpa_supplicant.conf是wifi账号和密码的配置文件，一般配置为：

ctrl_interface=/var/run/wpa_supplicant
update_config=1

network={
        ssid="iphone30promax"
        psk="12345678"
        scan_ssid=1
}

udhcpc运行时有个默认脚本，这个脚本需要你自己添加，udhcpc -h可查看到脚本默认路径

default.script文件：

#!/bin/sh

# udhcpc script edited by Tim Riker <Tim@Rikers.org>

[ -z "$1" ] && echo "Error: should be called from udhcpc" && exit 1

RESOLV_CONF="/etc/resolv.conf"
[ -e $RESOLV_CONF ] || touch $RESOLV_CONF
[ -n "$broadcast" ] && BROADCAST="broadcast $broadcast"
[ -n "$subnet" ] && NETMASK="netmask $subnet"

case "$1" in
        deconfig)
                /sbin/ifconfig $interface up
                /sbin/ifconfig $interface 0.0.0.0

                # drop info from this interface
                # resolv.conf may be a symlink to /tmp/, so take care
                TMPFILE=$(mktemp)
                grep -vE "# $interface\$" $RESOLV_CONF > $TMPFILE
                cat $TMPFILE > $RESOLV_CONF
                rm -f $TMPFILE

                if [ -x /usr/sbin/avahi-autoipd ]; then
                        /usr/sbin/avahi-autoipd -k $interface
                fi
                ;;

        leasefail|nak)
                if [ -x /usr/sbin/avahi-autoipd ]; then
                        /usr/sbin/avahi-autoipd -wD $interface --no-chroot
                fi
                ;;

        renew|bound)
                if [ -x /usr/sbin/avahi-autoipd ]; then
                        /usr/sbin/avahi-autoipd -k $interface
                fi
                /sbin/ifconfig $interface $ip $BROADCAST $NETMASK

                if [ -n "$router" ] ; then
                        echo "deleting routers"
                        while route del default gw 0.0.0.0 dev $interface 2> /dev/null; do
                                :
                        done

                        for i in $router ; do
                                route add default gw $i dev $interface
                        done
                fi

                # drop info from this interface
                # resolv.conf may be a symlink to /tmp/, so take care
                TMPFILE=$(mktemp)
                grep -vE "# $interface\$" $RESOLV_CONF > $TMPFILE
                cat $TMPFILE > $RESOLV_CONF
                rm -f $TMPFILE

                # prefer rfc3359 domain search list (option 119) if available
                if [ -n "$search" ]; then
                        search_list=$search
                elif [ -n "$domain" ]; then
                        search_list=$domain
                fi

                [ -n "$search_list" ] &&
                        echo "search $search_list # $interface" >> $RESOLV_CONF

                for i in $dns ; do
                        echo adding dns $i
                        echo "nameserver $i # $interface" >> $RESOLV_CONF
                done
                ;;
esac

HOOK_DIR="$0.d"
for hook in "${HOOK_DIR}/"*; do
    [ -f "${hook}" -a -x "${hook}" ] || continue
    "${hook}" "${@}"
done

exit 0

这几个文件我都已经上传到我的gitee。

希望我的文章有帮助到你。