一、介绍
dropbear作为一款基于ssh协议的轻量级sshd服务器，相比OpenSSH，其更简洁，更小巧，运行起来内存占用比也更小。在应用进程上，OpenSSH会开启两个sshd进程服务，而dropbear只开启一个进程，相较于OpenSSH，其对于硬件要求也更低，也更节约系统资源。
dropbear实现完整的SSH客户端和服务器版本2协议，不支持SSH版本1协议的向后兼容性，以节省空间和资源，并避免在SSH版本1的固有的安全漏洞。
dropbear主要有以下程序：
- 服务程序：dropbear（类似于Openssh的sshd）
- 客户程序：dbclinet（累世于Openssh的ssh）
- 密钥生成程序：dropbearkey
二、dropbear的编译安装：
安装准备：
1. 安装开发包组
[root@CentOS7 ~]#yum groupinstall Development tools -y
2. 下载dropbear-2017.75.tar.bz2
3. 将其dropbear进行解压缩，并查看安装自述文件
[root@CentOS7 /app]#tar xf dropbear-2017.75.tar.bz2
[root@CentOS7 /app/dropbear-2017.75]#less INSTALL README
Basic Dropbear build instructions:
- Edit options.h to set which features you want.
- Edit debug.h if you want any debug options (not usually required).
(If using a non-tarball copy, "autoconf; autoheader")
./configure (optionally with --disable-zlib or --disable-syslog,
or --help for other options)
Now compile:
make PROGRAMS="dropbear dbclient dropbearkey dropbearconvert scp"
And install (/usr/local/bin is usual default):
make PROGRAMS="dropbear dbclient dropbearkey dropbearconvert scp" install
(you can leave items out of the PROGRAMS list to avoid compiling them. If you
recompile after changing the PROGRAMS list, you *MUST* "make clean" before
recompiling - bad things will happen otherwise)
See MULTI for instructions on making all-in-one binaries.
If you want to compile statically, add "STATIC=1" to the make command-line.
Binaries can be stripped with "make strip"
============================================================================
If you're compiling for a 386-class CPU, you will probably need to add
CFLAGS=-DLTC_NO_BSWAP so that libtomcrypt doesn't use 486+ instructions.
============================================================================
INSTALL (file 1 of 2)...skipping...
Basic Dropbear build instructions:
- Edit options.h to set which features you want.
- Edit debug.h if you want any debug options (not usually required).
(If using a non-tarball copy, "autoconf; autoheader")
./configure (optionally with --disable-zlib or --disable-syslog,
or --help for other options)
Now compile:
make PROGRAMS="dropbear dbclient dropbearkey dropbearconvert scp"
And install (/usr/local/bin is usual default):
make PROGRAMS="dropbear dbclient dropbearkey dropbearconvert scp" install
4、对即将安装的软件进行配置，检查当前的环境是否满足要安装软件的依赖关系，对缺少依赖关系进行yum安装
[root@CentOS7 /app/dropbear-2017.75]#./configure
configure: error: *** zlib missing - install first or check config.log *** #显示其缺少zlib-devel
[root@CentOS7 /app/dropbear-2017.75]#yum install zlib-devel -y
5. 编译安装
make PROGRAMS="dropbear dbclient dropbearkey dropbearconvert scp"
make PROGRAMS="dropbear dbclient dropbearkey dropbearconvert scp" install
6. 创建目录/etc/dropbear/，生成key文件
[root@CentOS7 /usr/local/bin]#mkdir /etc/dropbear/
[root@CentOS7 /usr/local/bin]#dropbearkey -t rsa -f /etc/dropbear/dropbear_rsa_host_key
7. 启动dropbear，默认后台运行
[root@CentOS7 /usr/local/bin]#dropbear -E -p 2222 #-p指定端口
[17279] Sep 12 22:40:34 Failed loading /etc/dropbear/dropbear_dss_host_key
[17279] Sep 12 22:40:34 Failed loading /etc/dropbear/dropbear_ecdsa_host_key
[17280] Sep 12 22:40:34 Running in background```
[root@CentOS7 /usr/local/bin]#ss -ntl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:2222 *:*
LISTEN 0 128 *:22 *:*
LISTEN 0 10 127.0.0.1:25 *:*
LISTEN 0 128 :::2222 :::*
LISTEN 0 128 :::22 :::*
LISTEN 0 128 :::23 :::*
客户端：
[root@CentOS6 ~]#ssh 172.18.254.65 -p 2222
The authenticity of host '[172.18.254.65]:2222 ([172.18.254.65]:2222)' can't be established.
RSA key fingerprint is aa:06:2e:6d:0c:61:b6:e1:52:67:4e:19:4d:8e:fa:80.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '[172.18.254.65]:2222' (RSA) to the list of known hosts.
root@172.18.254.65's password:
[root@CentOS7 ~]# ##连接成功
服务端连接状态：
[root@CentOS7 /usr/local/bin]#[17294] Sep 12 22:44:45 Child connection from 172.18.254.55:37836
[17294] Sep 12 22:44:47 Password auth succeeded for 'root' from 172.18.254.55:37836
-F指定前台运行：
[root@CentOS7 ~]#dropbear -FE -p 2222
[17324] Sep 12 22:48:32 Failed loading /etc/dropbear/dropbear_dss_host_key
[17324] Sep 12 22:48:32 Failed loading /etc/dropbear/dropbear_ecdsa_host_key
[17324] Sep 12 22:48:32 Failed listening on '2222': Error listening: Address already in use
[17324] Sep 12 22:48:32 Early exit: No listening ports available.
