iptables 和允许的端口拒绝连接

Question

你能看出我做错了什么吗？在 Ubuntu Server 9.1 上，我试图允许非特权 IMAP 主机在端口 1143 上传输流量。

测试时连接被拒绝

telnet example.com 1143

但允许连接测试

telnet example.com 80

从我的电脑到远程互联网托管服务器。两个规则看起来相同并且彼此靠近，没有规则拒绝插入规则文件中的连接。我想不通。

iptables -L 返回这个：

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere            
REJECT     all  --  anywhere             127.0.0.0/8         reject-with icmp-port-unreachable 
ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED 
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:www 
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:https 
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:http-alt 
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:7070 
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:1143 
ACCEPT     tcp  --  anywhere             anywhere            state NEW tcp dpt:ssh 
ACCEPT     icmp --  anywhere             anywhere            icmp echo-request 
LOG        all  --  anywhere             anywhere            limit: avg 5/min burst 5 LOG level  debug prefix `iptables denied: ' 
REJECT     all  --  anywhere             anywhere            reject-with icmp-port-unreachable 

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         
REJECT     all  --  anywhere             anywhere            reject-with icmp-port-unreachable 

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere            

我的规则文件包含以下内容：

# Generated by iptables-save v1.4.4 on Wed May 26 19:08:34 2010
*nat
:PREROUTING ACCEPT [3556:217296]
:POSTROUTING ACCEPT [6909:414847]
:OUTPUT ACCEPT [6909:414847]
-A PREROUTING -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 8080 
-A PREROUTING -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 8080 
COMMIT
# Completed on Wed May 26 19:08:34 2010
# Generated by iptables-save v1.4.4 on Wed May 26 19:08:34 2010
*filter
:INPUT ACCEPT [1:52]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1:212]
-A INPUT -i lo -j ACCEPT 
-A INPUT -d 127.0.0.0/8 ! -i lo -j REJECT --reject-with icmp-port-unreachable 
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT 
-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT 
-A INPUT -p tcp -m tcp --dport 443 -j ACCEPT 
-A INPUT -p tcp -m tcp --dport 8080 -j ACCEPT 
-A INPUT -p tcp -m tcp --dport 7070 -j ACCEPT 
-A INPUT -p tcp -m tcp --dport 1143 -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT 
-A INPUT -p icmp -m icmp --icmp-type 8 -j ACCEPT 
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7 
-A INPUT -j REJECT --reject-with icmp-port-unreachable 
-A FORWARD -j REJECT --reject-with icmp-port-unreachable 
-A OUTPUT -j ACCEPT 
COMMIT
# Completed on Wed May 26 19:08:34 2010

Answer 1

Telnet 测试防火墙只有在有东西在那个端口上侦听时才有效。Ignacio 发布的 netstat 命令执行以下操作：netstat -ntlp | grep ':1143'

所以你需要启动服务，或者，你可以使用netcat之类的东西来制作一个监听端口：nc -l 1143作为临时测试。