限制SSH用户访问Linux中指定的目录
http://os.51cto.com/art/201703/534895.htm#topx
http://www.cnblogs.com/lykyl/archive/2011/03/10/1980304.html
采用ChrootDirectory设置需要注意
ChrootDirectory设置的目录及其所有的上级目录属主必须是root且只有属主能拥有写权限，也就是说权限最大设置只能是755。否则会报“fatal: bad ownership or modes for chroot directory”这样的错误。
用户目录下的链接文件失去作用。
useradd readonlyuser;echo -e "123456
123456
" |passwd readonlyuser
mkdir -p /ngbs/readonlyuser/dev/
cd /ngbs/readonlyuser/dev/
mknod -m 666 null c 1 3
mknod -m 666 tty c 5 0
mknod -m 666 zero c 1 5
mknod -m 666 random c 1 8
chown root:root /ngbs/readonlyuser
chmod 0755 /ngbs/readonlyuser
mkdir -p /ngbs/readonlyuser/bin
cp /bin/bash /ngbs/readonlyuser/bin/
mkdir -p /ngbs/readonlyuser/lib64/
cp /lib64/{libtinfo.so.5,libdl.so.2,libc.so.6,ld-linux-x86-64.so.2} /ngbs/readonlyuser/lib64/
mkdir /ngbs/readonlyuser/etc
cp -f /etc/{passwd,group} /ngbs/readonlyuser/etc/
tail -1 /ngbs/readonlyuser/etc/passwd >/tmp/1.txt ;cat /tmp/1.txt > /ngbs/readonlyuser/etc/passwd
注意：每次向系统添加更多 SSH 用户时，都需要将更新的帐户文件复制到 /ngbs/readonlyuser/etc 目录中。
vi /etc/ssh/sshd_config
在此文件中添加或修改下面这些行。
# override default of no subsystems
Subsystem ssh /usr/bin/ssh #这里改为ssh
# Example of overriding settings on a per-user basis
Match User readonlyuser 改为Match User readonlyuser
Match User readonlyuser 下面加上这一行 ChrootDirectory /ngbs/readonlyuser
也就是下面这样
# override default of no subsystems
Subsystem ssh /usr/bin/ssh
# Example of overriding settings on a per-user basis
Match User readonlyuser
ChrootDirectory /ngbs/readonlyuser
# X11Forwarding no
# AllowTcpForwarding no
重启 sshd 服务：
/etc/init.d/sshd restart
接下来，在 bin 目录中安装几个用户命令
cp /bin/ls /ngbs/readonlyuser/bin/
cp /bin/cat /ngbs/readonlyuser/bin/
cp /bin/more /ngbs/readonlyuser/bin/
cp /usr/bin/less /ngbs/readonlyuser/bin/
cp /usr/bin/head /ngbs/readonlyuser/bin/
cp /usr/bin/tail /ngbs/readonlyuser/bin/
ldd /bin/ls
ldd /bin/cat
ldd /bin/more
ldd /usr/bin/less
ldd /usr/bin/head
ldd /usr/bin/tail
/bin/cp /lib64/{libselinux.so.1,librt.so.1,libcap.so.2,libacl.so.1,libc.so.6,libdl.so.2,ld-linux-x86-64.so.2,libpthread.so.0,libattr.so.1,libtinfo.so.5,libpcre.so.0} /ngbs/readonlyuser/lib64/
测试 SSH 的 chroot 监狱
ssh readonlyuser@192.168.0.10
*/1 * * * * /usr/bin/rsync -a /ngbs/local/JmCash/log/* /ngbs/readonlyuser/log/
*/1 * * * * /usr/bin/rsync -a /ngbs/local/JmCash/logs/* /ngbs/readonlyuser/logs/
*/1 * * * * /usr/bin/rsync -a /ngbs/local/JmCash/phonelog/* /ngbs/readonlyuser/phonelog/
注意：如果是目录外做一个软链接到目录内是不行的，会报错 no such file or directory
ln -s /data/download /home/test
注意：sftp
