在我的 Linux 服务器（Ubuntu 8）中，我已经为 ntp 打开了端口 123。我已将其写入 /etc/iptables.rules：
:INPUT ACCEPT [7496:9080183]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [4393:322232]
[0:0] -A INPUT -p udp -m udp --sport 8100 -j ACCEPT
[0:0] -A INPUT -p udp -m udp --dport 8100 -j ACCEPT
[0:0] -I INPUT -p udp --dport 123 -j ACCEPT
[0:0] -I OUTPUT -p udp --sport 123 -j ACCEPT
COMMIT
但如果我启动这个命令：
nmap localhost -p123
回复我：
Starting Nmap 4.53 ( http://insecure.org ) at 2013-03-28 12:05 CET
Interesting ports on localhost (127.0.0.1):
PORT STATE SERVICE
123/tcp closed ntp
如果我吃这个
ntpdate -d it.pool.ntp.org
回复我：
28 Mar 11:07:31 ntpdate[5132]: ntpdate [email protected] Fri Dec 4 18:18:35 UTC 2009 (1)
transmit(212.45.144.59)
transmit(212.45.144.16)
transmit(2.228.72.62)
transmit(84.38.50.20)
transmit(212.45.144.59)
transmit(212.45.144.16)
transmit(2.228.72.62)
transmit(84.38.50.20)
transmit(212.45.144.59)
transmit(212.45.144.16)
transmit(2.228.72.62)
transmit(84.38.50.20)
transmit(212.45.144.59)
transmit(212.45.144.16)
transmit(2.228.72.62)
transmit(84.38.50.20)
transmit(212.45.144.59)
transmit(212.45.144.16)
transmit(2.228.72.62)
transmit(84.38.50.20)
212.45.144.59: Server dropped: no data
212.45.144.16: Server dropped: no data
2.228.72.62: Server dropped: no data
84.38.50.20: Server dropped: no data
server 212.45.144.59, port 123
stratum 0, precision 0, leap 00, trust 000
refid [212.45.144.59], delay 0.00000, dispersion 64.00000
transmitted 4, in filter 4
reference time: 00000000.00000000 Thu, Feb 7 2036 7:28:16.000
originate timestamp: 00000000.00000000 Thu, Feb 7 2036 7:28:16.000
transmit timestamp: d4fe94e6.3e0589ac Thu, Mar 28 2013 11:07:34.242
filter delay: 0.00000 0.00000 0.00000 0.00000
0.00000 0.00000 0.00000 0.00000
filter offset: 0.000000 0.000000 0.000000 0.000000
0.000000 0.000000 0.000000 0.000000
delay 0.00000, dispersion 64.00000
offset 0.000000
server 212.45.144.16, port 123
stratum 0, precision 0, leap 00, trust 000
refid [212.45.144.16], delay 0.00000, dispersion 64.00000
transmitted 4, in filter 4
reference time: 00000000.00000000 Thu, Feb 7 2036 7:28:16.000
originate timestamp: 00000000.00000000 Thu, Feb 7 2036 7:28:16.000
transmit timestamp: d4fe94e6.7138de6d Thu, Mar 28 2013 11:07:34.442
filter delay: 0.00000 0.00000 0.00000 0.00000
0.00000 0.00000 0.00000 0.00000
filter offset: 0.000000 0.000000 0.000000 0.000000
0.000000 0.000000 0.000000 0.000000
delay 0.00000, dispersion 64.00000
offset 0.000000
server 2.228.72.62, port 123
stratum 0, precision 0, leap 00, trust 000
refid [2.228.72.62], delay 0.00000, dispersion 64.00000
transmitted 4, in filter 4
reference time: 00000000.00000000 Thu, Feb 7 2036 7:28:16.000
originate timestamp: 00000000.00000000 Thu, Feb 7 2036 7:28:16.000
transmit timestamp: d4fe94e6.a46f049a Thu, Mar 28 2013 11:07:34.642
filter delay: 0.00000 0.00000 0.00000 0.00000
0.00000 0.00000 0.00000 0.00000
filter offset: 0.000000 0.000000 0.000000 0.000000
0.000000 0.000000 0.000000 0.000000
delay 0.00000, dispersion 64.00000
offset 0.000000
server 84.38.50.20, port 123
stratum 0, precision 0, leap 00, trust 000
refid [84.38.50.20], delay 0.00000, dispersion 64.00000
transmitted 4, in filter 4
reference time: 00000000.00000000 Thu, Feb 7 2036 7:28:16.000
originate timestamp: 00000000.00000000 Thu, Feb 7 2036 7:28:16.000
transmit timestamp: d4fe94e6.d7a22706 Thu, Mar 28 2013 11:07:34.842
filter delay: 0.00000 0.00000 0.00000 0.00000
0.00000 0.00000 0.00000 0.00000
filter offset: 0.000000 0.000000 0.000000 0.000000
0.000000 0.000000 0.000000 0.000000
delay 0.00000, dispersion 64.00000
offset 0.000000
28 Mar 11:07:35 ntpdate[5132]: no server suitable for synchronization found
我必须重新启动某些东西或者我的配置错误？
答案1
ntp 是 udp 而您正在扫描 tcp，这就是为什么它说它已关闭。
尝试这个
nmap -sT -sU -p 123 localhost
答案2
NTP 通过 UDP 工作。您需要运行以下命令：
[10:05:28] [root@dewa vol]# nmap -sU -P0 -p 123 127.0.0.1
Starting Nmap 5.51 ( http://nmap.org ) at 2013-03-28 10:05 UTC
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00030s latency).
PORT STATE SERVICE
123/udp open ntp
Nmap done: 1 IP address (1 host up) scanned in 0.07 seconds