为什么启用 ufw 后我无法 ping 任何域/主机名？
[root@ip-172-31-23-37 ec2-user]# ping google.com
ping: google.com: Name or service not known
[root@ip-172-31-23-37 ec2-user]# ufw disable
Firewall stopped and disabled on system startup
[root@ip-172-31-23-37 ec2-user]# ping google.com
PING google.com (74.125.24.100) 56(84) bytes of data.
64 bytes from 74.125.24.100 (74.125.24.100): icmp_seq=1 ttl=100 time=2.14 ms
64 bytes from 74.125.24.100 (74.125.24.100): icmp_seq=2 ttl=100 time=2.19 ms
^C
--- google.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 2.149/2.170/2.192/0.051 ms
[root@ip-172-31-23-37 ec2-user]# ufw enable
Command may disrupt existing ssh connections. Proceed with operation (y|n)? y
Firewall is active and enabled on system startup
[root@ip-172-31-23-37 ec2-user]# ping google.com
ping: google.com: Name or service not known
我禁用了除使用命令定义之外的所有传出流量ufw default deny outgoing。ufw status：
80 ALLOW OUT Anywhere
443 ALLOW OUT Anywhere
3306 ALLOW OUT Anywhere
2465 ALLOW OUT Anywhere
3306/tcp ALLOW OUT Anywhere
3306/udp ALLOW OUT Anywhere
127.0.0.1 3306 ALLOW OUT Anywhere
80 (v6) ALLOW OUT Anywhere (v6)
443 (v6) ALLOW OUT Anywhere (v6)
3306 (v6) ALLOW OUT Anywhere (v6)
2465 (v6) ALLOW OUT Anywhere (v6)
3306/tcp (v6) ALLOW OUT Anywhere (v6)
3306/udp (v6) ALLOW OUT Anywhere (v6)
我已经设置接受icmp到/etc/ufw/before.rules文件
# allow outbound icmp
-A ufw-before-output -p icmp -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
-A ufw-before-output -p icmp -m state --state ESTABLISHED,RELATED -j ACCEPT
答案1
您尚未允许出站 DNS 流量，因此无法将名称解析为 IP 地址。