msf > use auxiliary/scanner/portscan/syn
msf auxiliary(syn) > set RHOSTS 172.16.21.170 /*设定rhosts参数为172.16.21.170
RHOST => 172.16.21.170
msf auxiliary(syn) > set THREADS 50 /* 设定线程数为50
THREADS => 50
msf auxiliary(syn) > run
msf auxiliary(syn) > run
[*] TCP OPEN 172.16.21.170:135
[*] TCP OPEN 172.16.21.170:139
[*] TCP OPEN 172.16.21.170:445
[*] TCP OPEN 172.16.21.170:1025
[*] TCP OPEN 172.16.21.170:5000
[*] Scanned 1 of 1 hosts (100% complete)
[*] Auxiliary module execution completed
从上述结果中看到，利用metasploit的portscan/syn模块在172.16.21.170主机上发现了五个开放的端口。