我试图从运行基本Amazon Linux AMI的Amazon EC2实例之一访问https://test.httpapi.com webservice。 这是nc命令的输出：
[root@ec2-instance]# nc -v test.httpapi.com 80 nc: connect to test.httpapi.com port 80 (tcp) failed: No route to host [root@ec2-instance]# nc -v test.httpapi.com 443 nc: connect to test.httpapi.com port 443 (tcp) failed: No route to host [root@ec2-instance]# nc -v test.httpapi.com 22 nc: connect to test.httpapi.com port 22 (tcp) failed: Connection refused 所以，当我尝试端口80或443时，我得到“没有路由到主机”，但当我尝试ssh端口22（这是预期的）时，“连接被拒绝”。
但是，如果我尝试从本地机器（运行Ubuntu Linux），我可以成功连接到端口80和443：
me@my-laptop$ nc -v test.httpapi.com 80 Connection to test.httpapi.com 80 port [tcp/www] succeeded! me@my-laptop$ nc -v test.httpapi.com 443 Connection to test.httpapi.com 443 port [tcp/https] succeeded! me@my-laptop$ nc -v test.httpapi.com 22 nc: connect to test.httpapi.com port 22 (tcp) failed: Connection refused
在EC2实例上禁用iptables。
这里可能是什么问题？
问题不是EC2实例。 我也无法连接到主机：
MacBook-Pro-van-Bart:~ ikbenbart$ nc -v test.httpapi.com 80 nc: connect to test.httpapi.com port 80 (tcp) failed: Connection refused MacBook-Pro-van-Bart:~ ikbenbart$ nc -v test.httpapi.com 443 nc: connect to test.httpapi.com port 443 (tcp) failed: Connection refused MacBook-Pro-van-Bart:~ ikbenbart$ nc -v test.httpapi.com 22 nc: connect to test.httpapi.com port 22 (tcp) failed: Connection refused
你试图连接的主机是我的67.15.184.38 ：
MacBook-Pro-van-Bart:~ ikbenbart$ dig test.httpapi.com ; <<>> DiG 9.6.0-APPLE-P2 <<>> test.httpapi.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 46683 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;test.httpapi.com. IN A ;; ANSWER SECTION: test.httpapi.com. 28116 IN A 67.15.184.38 ;; Query time: 9 msec ;; SERVER: 192.168.220.52#53(192.168.220.52) ;; WHEN: Mon Jun 13 13:56:28 2011 ;; MSG SIZE rcvd: 50
但是这指向另一个主机：
MacBook-Pro-van-Bart:~ ikbenbart$ host 67.15.184.38 38.184.15.67.in-addr.arpa is an alias for 38.184.15.67.in-addr.ev1.opticaljungle.com. 38.184.15.67.in-addr.ev1.opticaljungle.com domain name pointer qmail-d.directi.com.
如果可能的话，看看你为67.15.184.38所做的设置。