定制linux内核+Busybox+dropbear实现远程登录
简单介绍下各阶段工作流程：
POST：开机后，加载BIOS信息（里面包含各硬件的相关信息）
BIOS（boot sequence）：选择（设备）启动项，然后读取MBR信息
Boot Loader：初始化硬件、建立内存空间映射，读取grub配置文件
Initrd：加载内核（硬件检测及初始化、挂载根文件系统）0→启动第一个进程init→该程序读出/etc/inittab、/etc/rc.d/rc.sysinit、/etc/rc.d/rc.local文件
Shell：启动/bin/login程序，进入登录界面
进入实验部分：
一、环境搭建
1、虚拟机（server1）上添加一个硬盘
2、在系统中给该磁盘进行分区
[root@localhost ~]# fdisk /dev/sdb
3、格式化
[root@localhost ~]# mke2fs -t ext4 /dev/sdb1 [root@localhost ~]# mke2fs -t ext4 /dev/sdb2 [root@localhost ~]# mkswap /dev/sdb3
4、挂载
[root@localhost ~]# mkdir /mnt/{sysroot,boot} #创建挂载目录
[root@localhost ~]# mount /dev/sdb1 /mnt/boot/
[root@localhost ~]# mount /dev/sdb2 /mnt/sysroot/
5、安装grub
[root@localhost ~]# grub-install --root-directory=/mnt /dev/sdb
6、创建linux各目录
[root@localhost ~]# cd /mnt/sysroot/ [root@localhost ~]# mkdir -pv etc/rc.d var/log root proc sys srv boot mnt tmp home dev lib lib64
二、编译内核
[root@localhost ~]# tar xf linux-3.13.6.tar.xz -C /usr/src/ #解压 [root@localhost ~]# cd /usr/src/ [root@localhost src]# ln -s linux-3.13.6 linux #创建软链接 [root@localhost src]# cd linux [root@localhost linux]# yum groupinstall "Development Tools" -y #安装开发包组 [root@localhost linux]# make allnoconfig #重置配置选项 [root@localhost linux]# make menuconfig
如果make menuconfig时报错：
提示：缺少ncurses-devel库文件
[root@localhost linux]# yum -y install ncurses-devel [root@localhost linux]# make menuconfig #再次进行
[*] 64 bit kernel #64位支持 [*] gerernal setup () local version - append to kernel release #版本号 [*] Enable loadable modual support #允许模块加载 -> Progressor type and features Processor Family(Core 2/newer Xeon) #自行选择处理器类型 [*] Symmetric multi-processing support #支持多核 -> Bus Options(PCI etc.) [*] PCI support #支持PCI总线 -> File system [*] The Extended 4 (ext) filesystem #支持ext4文件系统 -> Executable file formats / Emulations #可执行文件系统 [*] Kernel support for ELF binaries #支持ELF二进制程序 [*] Kernel support for scripts starting with #! #支持脚本 [*] Networking support -> Networking options [*] Unix domain sockets [*] UNIX: socket monitoring interface [*] TCP/IP networking [*] IP: multicasting #ip多播协议 [*] IP: advanced router #高级路由协议 [*] IP: kernel level autoconfiguration #内核级别配置 [*] IP: DHCP support #DHCP服务 [*] IP: BOOTP support [*] IP: RARP Support #RARP协议 [*] IP: TCP syncookie support #tcp同步状态 -> Device Drivers -> Gernal Driver Options [*] Maintain a devtmpfs filesystem to mount at /dev #使用devtmpfs机制挂载设备文件 [*] Automount devtmpfs at /dev, after the kernel mounted the rootfs #自动挂载 -> SCSI device support [*] SCSI deveice support [*] SCSI disk support [*] Fusion MPT device support #支持虚拟磁盘 [*] Fusion MPT ScsiHost drivers for SPI #虚拟磁盘 [*] Fusion MPT misc device (ioctl) driver #磁盘初始化 [*] Network device support [*] Network core driver support #网络核心驱动 [*] Ethernet driver support #以太网卡驱动 [*] Intel devices (NEW) [*] Intel(R) PRO/1000 Gigabit Ethernet support [*] Intel(R) PRO/1000 PCI-Express Gigabit Ethernet support -> Input Device support [*] Mouse interface [*] Keyboards #键盘 [*] Mice #ps/2 [*] USB support [*] Support for Host-side USB [*] xHCI HCD (USB 2.0) support [*] EHCI HCD (USB 3.0) support [*] OHCI HCD (USB 1.1) support
[root@localhost linux]# make bzImage -j 3 #只编译内核，并且使用3个线程 [root@localhost linux]# cp arch/x86_64/boot/bzImage /mnt/boot/ #拷贝内核
三、安装busybox
安装busybox需要依赖glibc-static
安装glibc-static 包在DVD2中，如何没有DVD2比如我..,自己搭建网络yum源安装
root@localhost ~]# wget http://mirrors.163.com/.help/CentOS6-Base-163.repo 这是网易yum源的配置文件 [root@localhost ~]# yum clean all /#生效刚刚加载的yum仓库 [root@localhost ~]# yum -y install glibc-static [root@localhost ~]# tar xf busybox-1.22.1.tar.bz2 [root@localhost ~]# cd busybox-1.22.1 [root@localhost busybox-1.22.1]# make menuconfig
-> Busybox Settings -> Build Options [*] Build BusyBox as a static binary (no shared libs)
[root@localhost busybox-1.22.1]# make && make install [root@localhost busybox-1.22.1]# cp -a _install/* /mnt/sysroot/
提供grub.conf文件：
[root@localhost ~]# vim /mnt/boot/grub/grub.conf default=0 timeout=5 title Linux (3.13.6) root (hd0,0) kernel /bzImage ro root=/dev/sda2 init=/sbin/init [root@localhost ~]# sync #把内存缓冲区的数据立即写入磁盘中
测试：
添加新的虚拟机（server2） 注意选择磁盘时要选择之前创建的磁盘
添加完成后，把server1挂起或关机,然后server2开机
启动正常，但提示没有初始化文件
四、提供初始化文件（etc/fstab etc/inittab etc/rc.d/rc.sysinit）
[root@localhost sysroot]# vim etc/fstab /dev/sdb1 /boot ext4 defaults 0 0 /dev/sdb2 / ext4 defaults 0 0 /dev/sdb3 swap swap defaults 0 0 proc /proc proc defaults 0 0 sysfs /sys sysfs defaults 0 0
[root@localhost sysroot]# vim etc/inittab ::sysinit:/etc/rc.d/rc.sysinit ::respawn:/sbin/getty 19200 tty1 ::respawn:/sbin/getty 19200 tty2 ::respawn:/sbin/getty 19200 tty3 ::respawn:/sbin/getty 19200 tty4 ::respawn:/sbin/getty 19200 tty5 ::respawn:/sbin/getty 19200 tty6 ::ctrlaltdel:/sbin/reboot ::shutdown:/bin/umount -a -r
[root@localhost sysroot]# vim etc/rc.d/rc.sysinit #!/bin/sh # echo -e "\tWelcome to \033[36mLinux\033[0m" [ -r /etc/sysconfig/network ] && . /etc/sysconfig/network [ -z "$HOSTNAME" -o "$HOSTNAME" == "(none)" ] && HOSTNAME=localhost /bin/hostname $HOSTNAME mount -a#基于/etc/fstab文件挂载设备 mdev -s#挂载内核所需设备文件 mount -o remount -rw / #把根挂载成可读写 ifconfig lo 127.0.0.1#配置网卡信息 ifconfig eth0 192.168.199.222 #配置网卡信息 export PS1="[\u@\h \w]$ " #导出PS1路径 export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin" #修改环境变量 [root@localhost sysroot]# chmod +x etc/rc.d/rc.sysinit
提供账号和密码文件：
[root@localhost sysroot]# head -1 /etc/passwd > etc/passwd [root@localhost sysroot]# vim etc/passwd [root@localhost sysroot]# head -1 /etc/group > etc/group [root@localhost sysroot]# head -1 /etc/shadow > etc/shadow [root@localhost sysroot]# chmod 400 etc/shadow
提供认证库文件：
[root@localhost ~]# cp -d /lib64/libnss_files* /mnt/sysroot/lib64/ [root@localhost ~]# cp -d /usr/lib64/libnss3.so /mnt/sysroot/usr/lib64/ [root@localhost ~]# mkdir /mnt/sysroot/usr/lib64 [root@localhost ~]# cp -d /usr/lib64/libnss3.so /mnt/sysroot/usr/lib64/ [root@localhost~]#cp -d /usr/lib64/libnss_files.so /mnt/sysroot/usr/lib64/ [root@localhost ~]# cp /etc/nsswitch.conf /mnt/sysroot/etc/ [root@localhost ~]# cp /etc/shells /mnt/sysroot/etc/
提供主机名：
[root@localhost sysroot]# mkdir etc/sysconfig [root@localhost sysroot]# vim etc/sysconfig/network HOSTNAME=biao.com [root@localhost sysroot]# sync
测试：
本地登陆成功！
五、提供ssh服务
[root@localhost ~]# tar xf dropbear-2016.73.tar.bz2 [root@localhost ~]# cd dropbear-2016.73 [root@localhost dropbear-2016.73]# ./configure
预编译时如果报如下错误：
#yum -y install zlib-devel #安装缺少的库 #./configure #再次预编译 [root@localhost dropbear-2016.73]# make PROGRAMS="dropbear dbclient dropbearkey scp" [root@localhost dropbear-2016.73]# make PROGRAMS="dropbear dbclient dropbearkey dropbearconvert scp" install
命令移植脚本：
#!/bin/bash
aimDir=/mnt/sysroot
cmdInput() {
if which $cmd &> /dev/null;then
cmdPath=`which --skip-alias $cmd`
else
echo "No such command."
return 5
fi
}
cpCmd() {
cmdDir=`dirname $cmdPath`
[ -d ${aimDir}${cmdDir} ] || mkdir -p ${aimDir}${cmdDir}
[ -f $cmdPath ] && cp $cmdPath ${aimDir}${cmdDir}
}
cpLib() {
for libPath in `ldd $cmdPath | grep -o "/[^[:space:]]\{1,\}"`;do
libDir=`dirname $libPath`
[ -d ${aimDir}${libDir} ] || mkdir -p ${aimDir}${libDir}
[ -f $libPath ] && cp $libPath ${aimDir}${libDir}
done
}
echo "You can input [q|Q] quit."
while true;do
read -p "Enter a command: " cmd
if [[ "$cmd" =~ \(|q|Q|\) ]];then
echo "You choose quit."
exit 0
fi
cmdInput
[ $? -eq 5 ] && continue
cpCmd
cpLib
[ $? -eq 0 ] && echo -e "\033[36mCopy successful.\033[0m"
Done
移植所需的命令：
[root@localhost ~]# bash cp.sh You can input [q|Q] quit. Enter a command: dropbear Copy successful. Enter a command: dropbearkey Copy successful. Enter a command: q You choose quit.
生成密钥：
[root@localhost ~]# mkdir /mnt/sysroot/etc/dropbear [root@localhost ~]# dropbearkey -t rsa -f /mnt/sysroot/etc/dropbear/dropbear_rsa_host_key -s 2048 [root@localhost ~]# dropbearkey -t dss -f /mnt/sysroot/etc/dropbear/dropbear_dss_host_key
创建pid文件存放目录：
[root@localhost ~]# mkdir /mnt/sysroot/var/run
挂载pts：
[root@localhost sysroot]# mkdir dev/pts [root@localhost sysroot]# vim etc/fstab ........ #上面省略 devpts /dev/pts devpts defaults 0 0
提供服务脚本：
[root@localhost sysroot]# mkdir etc/rc.d/init.d
[root@localhost sysroot]# vim etc/rc.d/init.d/dropbear
#!/bin/bash
#
# description: dropbear ssh daemon
# chkconfig: 2345 66 33
#
dsskey=/etc/dropbear/dropbear_dss_host_key
rsakey=/etc/dropbear/dropbear_rsa_host_key
lockfile=/var/lock/subsys/dropbear
pidfile=/var/run/dropbear.pid
dropbear=/usr/local/sbin/dropbear
dropbearkey=/usr/local/bin/dropbearkey
[ -r /etc/rc.d/init.d/functions ] && . /etc/rc.d/init.d/functions
[ -r /etc/sysconfig/dropbear ] && . /etc/sysconfig/dropbear
keysize=1024
port=22
gendsskey() {
[ -d /etc/dropbear ] || mkdir /etc/dropbear
echo -n "Starting generate the dss key: "
$dropbearkey -t dss -f $dsskey &> /dev/null
RETVAL=$?
if [ $RETVAL -eq 0 ]; then
success
echo
return 0
else
failure
echo
return 1
fi
}
genrsakey() {
[ -d /etc/dropbear ] || mkdir /etc/dropbear
echo -n "Starting generate the rsa key: "
$dropbearkey -t rsa -s $keysize -f $rsakey &> /dev/null
RETVAL=$?
if [ $RETVAL -eq 0 ]; then
success
echo
return 0
else
failure
echo
return 1
fi
}
start() {
[ -e $dsskey ] || gendsskey
[ -e $rsakey ] || genrsakey
if [ -e $lockfile ]; then
echo -n "dropbear daemon is already running: "
success
echo
exit 0
fi
echo -n "Starting dropbear: "
daemon --pidfile="$pidfile" $dropbear -p $port -d $dsskey -r $rsakey
RETVAL=$?
echo
if [ $RETVAL -eq 0 ]; then
touch $lockfile
return 0
else
rm -f $lockfile $pidfile
return 1
fi
}
stop() {
if [ ! -e $lockfile ]; then
echo -n "dropbear service is stopped: "
success
echo
exit 1
fi
echo -n "Stopping dropbear daemon: "
killproc dropbear
RETVAL=$?
echo
if [ $RETVAL -eq 0 ]; then
rm -f $lockfile $pidfile
return 0
else
return 1
fi
}
status() {
if [ -e $lockfile ]; then
echo "dropbear is running..."
else
echo "dropbear is stopped..."
fi
}
usage() {
echo "Usage: dropbear {start|stop|restart|status|gendsskey|genrsakey}"
}
case $1 in
start)
start ;;
stop)
stop ;;
restart)
stop
start
;;
status)
status
;;
gendsskey)
gendsskey
;;
genrsakey)
genrsakey
;;
*)
usage
;;
esac
[root@localhost sysroot]# chmod +x etc/rc.d/init.d/dropbear
[root@localhost sysroot]# cp /etc/rc.d/init.d/functions etc/rc.d/init.d/
[root@localhost sysroot]# cd etc/rc.d/
[root@localhost rc.d]# ln -s init.d/dropbear dropbear.start
[root@localhost rc.d]# ln -s init.d/dropbear dropbear.stop
[root@localhost rc.d]# echo "/etc/rc.d/*.start start" >> rc.sysinit
关机脚本
[root@localhost rc.d]# vim rc.sysdown #!/bin/sh # sync #把内存缓冲区的数据立即写入磁盘中 sleep 3 #给系统3秒的写入时间 /etc/rc.d/*.stop stop umount -a -r Poweroff [root@localhost rc.d] vim /mnt/sysroot/etc/inittab ::shutdown:/etc/rc.d/rc.sysdown #最后一行修改成这样
测试：
服务开机启动
ssh远程登录成功：
以上实验全部完成！！！！！！！！！
![[Zabbix问题解决]Zabbix discoverer processes 75% busy](https://s3.51cto.com/wyfs02/M02/85/F8/wKioL1exPxeyYcw_AACDZp7PX-U776.png)
