我用的 nmap 3.0(Linux下的)，这个命令参数：
nmap -v -sU -p 27015-27050 202.103.82.6
解释如下：
-v 详细地输出
-sU 扫描UDP端口
-p 27015-27050 指定端口范围
后面是IP地址，下面是真实的输出结果：
[root@rh72 root]# nmap -v -sU -p 27015 202.103.82.6
Starting nmap V. 3.00 ( www.insecure.org/nmap/ )
Host (202.103.82.6) appears to be up ... good.
Initiating UDP Scan against (202.103.82.6)
The UDP Scan took 0 seconds to scan 1 ports.
Adding open port 27015/udp
Interesting ports on (202.103.82.6):
Port State Service
27015/udp open halflife
Nmap run completed -- 1 IP address (1 host up) scanned in 1 second
[root@rh72 root]#
