Linux 怎样踢掉让SSH登录的用户下线

w命令查看了下，发现服务器被入侵，怎样踢掉登录的用户。怎样踢掉112开头的用户

 23:15:06 up 17 min,  3 users,  load average: 0.08, 0.05, 0.02
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
root     tty1                      23:00   12:56   0.04s  0.03s -bash
root     pts/0    112.192.19.108   23:15    2.00s  0.01s  0.00s w
root     pts/1    221.10.28.222    23:04   57.00s  0.14s  0.14s -bash