☰

iptables 阻止我连接

tag-icon • tag-icon networking iptables firewall
iptables 阻止我连接

我正在使用 Ubuntu 18.04，我当前的 iptables 规则来自这个问题；iptables -L给出：

Chain INPUT (policy DROP)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere             state RELATED,ESTABLISHED
REJECT     all  --  anywhere             anywhere             reject-with icmp-port-unreachable

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

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

有了这些，我哪儿也连接不了。我必须刷新列表并再次接受（从头开始）才能恢复连接。为什么这些不起作用？

答案1

您需要允许本地环回接口：

sudo iptables -A INPUT -i lo -j ACCEPT

有时，进程间通信会通过环回接口进行。请参见这里有关环回接口的更多信息。

编辑：所以我的其中一台测试电脑上就有这个：

doug@s17:~$ sudo iptables -v -x -n -L

Chain INPUT (policy DROP 0 packets, 0 bytes)
    pkts      bytes target     prot opt in     out     source               destination
      94     9843 ACCEPT     all  --  lo     *       0.0.0.0/0            0.0.0.0/0
    5093  6056565 ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0            state RELATED,ESTABLISHED
       8      613 REJECT     all  --  *      *       0.0.0.0/0            0.0.0.0/0            reject-with icmp-port-unreachable

Chain FORWARD (policy DROP 0 packets, 0 bytes)
    pkts      bytes target     prot opt in     out     source               destination
       0        0 REJECT     all  --  *      *       0.0.0.0/0            0.0.0.0/0            reject-with icmp-port-unreachable

Chain OUTPUT (policy ACCEPT 3904 packets, 321224 bytes)
    pkts      bytes target     prot opt in     out     source               destination

现在，如果我想进一步了解被拒绝的数据包，我也可以记录它们：

sudo iptables --insert INPUT 3 --jump LOG --log-prefix "INPUT-REJECT:" --log-level info

然后（在更多拒绝之后）查看 /var/log/syslog：

Dec 12 14:18:42 s17 kernel: [2007598.577383] INPUT-REJECT:IN=ens5 OUT= MAC=ff:ff:ff:ff:ff:ff:00:21:9b:f9:21:26:08:00 SRC=192.168.111.101 DST=255.255.255.255 LEN=42 TOS=0x00 PREC=0x00 TTL=1 ID=4970 PROTO=UDP SPT=55705 DPT=3289 LEN=22
Dec 12 14:18:42 s17 kernel: [2007598.695347] INPUT-REJECT:IN=ens5 OUT= MAC=ff:ff:ff:ff:ff:ff:00:21:9b:f9:21:26:08:00 SRC=192.168.111.101 DST=255.255.255.255 LEN=42 TOS=0x00 PREC=0x00 TTL=1 ID=4971 PROTO=UDP SPT=55708 DPT=3289 LEN=22
Dec 12 14:18:43 s17 kernel: [2007599.014201] INPUT-REJECT:IN=ens5 OUT= MAC=ff:ff:ff:ff:ff:ff:00:21:9b:f9:21:26:08:00 SRC=192.168.111.101 DST=255.255.255.255 LEN=42 TOS=0x00 PREC=0x00 TTL=1 ID=4972 PROTO=UDP SPT=55712 DPT=3289 LEN=22

我观察到它们只是来自我现在正在打字的这台计算机的广播数据包。

相关内容