准备编译环境，基于Ubuntu18系统：
sudo apt-get install git git-doc subversion build-essential flex wget gawk unzip man file python2.7 zlib1g-dev libssl-dev libncurses5-dev ocaml-nox
下载代码：
git clone --branch qsdk-11.3-ipq60xx-4.4 https://github.com/8devices/openwrt-8devices.git
编译：
cd openwrt-8devices
./quick_start.sh 8dev_mango_open -c
如遇到如下问题：
error: dereferencing pointer to incomplete type 'RSA {aka struct rsa_st}'
下载如下补丁
https://github.com/openwrt/openwrt/commit/70b104f98c0657323b28fce140b73a94bf3eb756#diff-ad001f3a51a1d957d5013650f14df0cb
保存到如下路径并命令为
tools/mkimage/patches/210-openssl-1.1.x-compat.patch
重新make
dropbear 修改源代码，并更新压缩包
/home/meng/ipq/openwrt-8devices/dl/dropbear-2019.78.tar.bz2
重新编译dropbear
make package/network/services/dropbear/clean
make package/network/services/dropbear/compile
