linux tips

检查空口令:
awk -F: '($2 == "") { print $1 }' /etc/shadow
正常执行后应该没有任何显示.
如果是发现有输出显示的话就证明这个用户没有口令.
执行例子:
root@testpc:[/root]awk -F: '($2 == "") { print $1 }' /etc/shadow
test

root@testpc:[/root]cat /etc/shadow|grep test
test::13251:0:99999:7:::

检查tcp/udp所有监听的服务以及进程名称:

root@testpc:[/etc/pam.d]netstat -tulp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name   
tcp        0      0 *:32768                     *:*                         LISTEN      1060/rpc.statd      
tcp        0      0 testpc:32769                *:*                         LISTEN      1197/xinetd         
tcp        0      0 *:sunrpc                    *:*                         LISTEN      1041/portmap        
tcp        0      0 *:auth                      *:*                         LISTEN      1197/xinetd         
tcp        0      0 *:ssh                       *:*                         LISTEN      1183/sshd           
tcp        0      0 testpc:ipp                  *:*                         LISTEN      1161/cupsd          
tcp        0      0 testpc:smtp                 *:*                         LISTEN      1217/sendmail: acce
udp        0      0 *:32768                     *:*                                     1060/rpc.statd      
udp        0      0 *:812                       *:*                                     1060/rpc.statd      
udp        0      0 *:sunrpc                    *:*                                     1041/portmap        
udp        0      0 *:ipp                       *:*                                     1161/cupsd