udhcp 服务介绍

发布时间：2024-11-17 更新时间：2026-02-08 总字数：658 阅读时间：2m 作者：谢先斌IP：上海网址

busybox 自带的 udhcpd 和 udhcpc 提供不完整的 DHCP 服务器和客户端，它们只是实现了 DHCP 协议的一部分，并且它们的功能有限。

介绍

udhcpd DHCP 服务器
udhcpc DHCP 客户端

udhcpd

udhcpd -f /etc/udhcpd.conf

udhcpc

udhcpc -b -i $interface --script=/usr/share/udhcpc/default.script # -q

说明：

通过 script 指定的脚本，配置 IP、route、DNS 等

help

udhcpc --help ...

$ udhcpc --help
BusyBox v1.24.2 (2019-07-03 11:13:35 EEST) multi-call binary.

Usage: udhcpc [-fbqvRB] [-t N] [-T SEC] [-A SEC/-n]
        [-i IFACE] [-s PROG] [-p PIDFILE]
        [-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]...

        -i,--interface IFACE    Interface to use (default eth0)
        -s,--script PROG        Run PROG at DHCP events (default /usr/share/udhcpc/default.script)
        -p,--pidfile FILE       Create pidfile
        -B,--broadcast          Request broadcast replies
        -t,--retries N          Send up to N discover packets (default 3)
        -T,--timeout SEC        Pause between packets (default 3)
        -A,--tryagain SEC       Wait if lease is not obtained (default 20)
        -n,--now                Exit if lease is not obtained
        -q,--quit               Exit after obtaining lease
        -R,--release            Release IP on exit
        -f,--foreground         Run in foreground
        -b,--background         Background if lease is not obtained
        -S,--syslog             Log to syslog too
        -r,--request IP         Request this IP address
        -o,--no-default-options Don't request any options (unless -O is given)
        -O,--request-option OPT Request option OPT from server (cumulative)
        -x OPT:VAL              Include option OPT in sent packets (cumulative)
                                Examples of string, numeric, and hex byte opts:
                                -x hostname:bbox - option 12
                                -x lease:3600 - option 51 (lease time)
                                -x 0x3d:0100BEEFC0FFEE - option 61 (client id)
        -F,--fqdn NAME          Ask server to update DNS mapping for NAME
        -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')
        -C,--clientid-none      Don't send MAC as client identifier
        -v                      Verbose
Signals:
        USR1    Renew lease
        USR2    Release lease

script 支持的环境变量

	$HOME		- The set $HOME env or "/"
	$PATH		- the set $PATH env or "/bin:/usr/bin:/sbin:/usr/sbin"
	$1		- What action the script should perform
	interface	- The interface this was obtained on
	ip		- The obtained IP
	siaddr		- The bootp next server option
	sname		- The bootp server name option
	boot_file	- The bootp boot file option
	subnet		- The assigend subnet mask
	timezone	- Offset in seconds from UTC
	router		- A list of routers   # $router 获取路由 ips 信息
	timesvr		- A list of time servers
	namesvr		- A list of IEN 116 name servers
	dns		- A list of DNS server
	logsvr		- A list of MIT-LCS UDP log servers
	cookiesvr	- A list of RFC 865 cookie servers
	lprsvr		- A list of LPR servers
	hostname	- The assigned hostname
	bootsize	- The length in 512 octect blocks of the bootfile
	domain		- The domain name of the network
	swapsvr		- The IP address of the client's swap server
	rootpath	- The path name of the client's root disk
	ipttl		- The TTL to use for this network
	mtu		- The MTU to use for this network
	broadcast	- The broadcast address for this network
	ntpsrv		- A list of NTP servers
	wins		- A list of WINS servers
	lease		- The lease time, in seconds
	dhcptype	- DHCP message type (safely ignored)
	serverid	- The IP of the server
	message		- Reason for a DHCPNAK
	tftp		- The TFTP server name
	bootfile	- The bootfile name

重新获取 IP

参考

udhcpc also responds to SIGUSR1 and SIGUSR2. SIGUSR1 will force a renew state,
and SIGUSR2 will force a release of the current lease, and cause udhcpc to
go into an inactive state (until it is killed, or receives a SIGUSR1). You do
not need to sleep between sending signals, as signals received are processed
sequencially in the order they are received.

# Release
kill -s USR2 udhcpc

# Renew
kill -s USR1 udhcpc

udhcp 服务介绍

介绍

udhcpd

udhcpc

help

udhcpc --help ...

script 支持的环境变量

重新获取 IP

Help

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