我正在尝试向我的服务器发送测试电子邮件，而日志中显示的内容都是 UFW 阻止了这些测试电子邮件的来源 IP，UFW 设置为允许所有必需的电子邮件端口。我没有对 UFW 进行任何更改，几天前一切都正常。
为什么会发生这种情况？我该怎么做才能解决这个问题？
UFW 设置：
To Action From
-- ------ ----
22 LIMIT IN Anywhere
80/tcp ALLOW IN Anywhere
443 ALLOW IN Anywhere
6789 DENY IN Anywhere
3306 DENY IN Anywhere
993 ALLOW IN Anywhere
995 ALLOW IN Anywhere
587 ALLOW IN Anywhere
465 ALLOW IN Anywhere
25 ALLOW IN Anywhere
22 LIMIT IN Anywhere (v6)
80/tcp ALLOW IN Anywhere (v6)
443 ALLOW IN Anywhere (v6)
6789 DENY IN Anywhere (v6)
3306 DENY IN Anywhere (v6)
993 ALLOW IN Anywhere (v6)
995 ALLOW IN Anywhere (v6)
587 ALLOW IN Anywhere (v6)
465 ALLOW IN Anywhere (v6)
25 ALLOW IN Anywhere (v6)
而且它似乎不仅仅是端口 25，UFW 似乎也对大量不同的 IP 执行了 [UFW BLOCK]。
iptables-save 的输出：
# Generated by iptables-save v1.4.21 on Mon Jun 5 20:44:01 2017
*mangle
:PREROUTING ACCEPT [65948:34120231]
:INPUT ACCEPT [65948:34120231]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [62283:57804370]
:POSTROUTING ACCEPT [62283:57804370]
COMMIT
# Completed on Mon Jun 5 20:44:01 2017
# Generated by iptables-save v1.4.21 on Mon Jun 5 20:44:01 2017
*nat
:PREROUTING ACCEPT [4339:300646]
:INPUT ACCEPT [901:55631]
:OUTPUT ACCEPT [780:49032]
:POSTROUTING ACCEPT [780:49032]
COMMIT
# Completed on Mon Jun 5 20:44:01 2017
# Generated by iptables-save v1.4.21 on Mon Jun 5 20:44:01 2017
*filter
:INPUT DROP [315:21392]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [1:52]
:ufw-after-forward - [0:0]
:ufw-after-input - [0:0]
:ufw-after-logging-forward - [0:0]
:ufw-after-logging-input - [0:0]
:ufw-after-logging-output - [0:0]
:ufw-after-output - [0:0]
:ufw-before-forward - [0:0]
:ufw-before-input - [0:0]
:ufw-before-logging-forward - [0:0]
:ufw-before-logging-input - [0:0]
:ufw-before-logging-output - [0:0]
:ufw-before-output - [0:0]
:ufw-logging-allow - [0:0]
:ufw-logging-deny - [0:0]
:ufw-not-local - [0:0]
:ufw-reject-forward - [0:0]
:ufw-reject-input - [0:0]
:ufw-reject-output - [0:0]
:ufw-skip-to-policy-forward - [0:0]
:ufw-skip-to-policy-input - [0:0]
:ufw-skip-to-policy-output - [0:0]
:ufw-track-input - [0:0]
:ufw-track-output - [0:0]
:ufw-user-forward - [0:0]
:ufw-user-input - [0:0]
:ufw-user-limit - [0:0]
:ufw-user-limit-accept - [0:0]
:ufw-user-logging-forward - [0:0]
:ufw-user-logging-input - [0:0]
:ufw-user-logging-output - [0:0]
:ufw-user-output - [0:0]
-A INPUT -j ufw-before-logging-input
-A INPUT -j ufw-before-input
-A INPUT -j ufw-after-input
-A INPUT -j ufw-after-logging-input
-A INPUT -j ufw-reject-input
-A INPUT -j ufw-track-input
-A FORWARD -j ufw-before-logging-forward
-A FORWARD -j ufw-before-forward
-A FORWARD -j ufw-after-forward
-A FORWARD -j ufw-after-logging-forward
-A FORWARD -j ufw-reject-forward
-A OUTPUT -j ufw-before-logging-output
-A OUTPUT -j ufw-before-output
-A OUTPUT -j ufw-after-output
-A OUTPUT -j ufw-after-logging-output
-A OUTPUT -j ufw-reject-output
-A OUTPUT -j ufw-track-output
-A ufw-after-input -p udp -m udp --dport 137 -j ufw-skip-to-policy-input
-A ufw-after-input -p udp -m udp --dport 138 -j ufw-skip-to-policy-input
-A ufw-after-input -p tcp -m tcp --dport 139 -j ufw-skip-to-policy-input
-A ufw-after-input -p tcp -m tcp --dport 445 -j ufw-skip-to-policy-input
-A ufw-after-input -p udp -m udp --dport 67 -j ufw-skip-to-policy-input
-A ufw-after-input -p udp -m udp --dport 68 -j ufw-skip-to-policy-input
-A ufw-after-input -m addrtype --dst-type BROADCAST -j ufw-skip-to-policy-input
-A ufw-after-logging-forward -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW BLOCK] "
-A ufw-after-logging-input -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW BLOCK] "
-A ufw-before-forward -j ufw-user-forward
-A ufw-before-input -i lo -j ACCEPT
-A ufw-before-input -m state --state RELATED,ESTABLISHED -j ACCEPT
-A ufw-before-input -m state --state INVALID -j ufw-logging-deny
-A ufw-before-input -m state --state INVALID -j DROP
-A ufw-before-input -p icmp -m icmp --icmp-type 3 -j ACCEPT
-A ufw-before-input -p icmp -m icmp --icmp-type 4 -j ACCEPT
-A ufw-before-input -p icmp -m icmp --icmp-type 11 -j ACCEPT
-A ufw-before-input -p icmp -m icmp --icmp-type 12 -j ACCEPT
-A ufw-before-input -p icmp -m icmp --icmp-type 8 -j ACCEPT
-A ufw-before-input -p udp -m udp --sport 67 --dport 68 -j ACCEPT
-A ufw-before-input -j ufw-not-local
-A ufw-before-input -d 224.0.0.251/32 -p udp -m udp --dport 5353 -j ACCEPT
-A ufw-before-input -d 239.255.255.250/32 -p udp -m udp --dport 1900 -j ACCEPT
-A ufw-before-input -j ufw-user-input
-A ufw-before-output -o lo -j ACCEPT
-A ufw-before-output -m state --state RELATED,ESTABLISHED -j ACCEPT
-A ufw-before-output -j ufw-user-output
-A ufw-logging-allow -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW ALLOW] "
-A ufw-logging-deny -m state --state INVALID -m limit --limit 3/min --limit-burst 10 -j RETURN
-A ufw-logging-deny -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW BLOCK] "
-A ufw-not-local -m addrtype --dst-type LOCAL -j RETURN
-A ufw-not-local -m addrtype --dst-type MULTICAST -j RETURN
-A ufw-not-local -m addrtype --dst-type BROADCAST -j RETURN
-A ufw-not-local -m limit --limit 3/min --limit-burst 10 -j ufw-logging-deny
-A ufw-not-local -j DROP
-A ufw-skip-to-policy-forward -j DROP
-A ufw-skip-to-policy-input -j DROP
-A ufw-skip-to-policy-output -j ACCEPT
-A ufw-track-output -p tcp -m state --state NEW -j ACCEPT
-A ufw-track-output -p udp -m state --state NEW -j ACCEPT
-A ufw-user-input -p tcp -m tcp --dport 22 -m state --state NEW -m recent --set --name DEFAULT --mask 255.255.255.255 --rsource
-A ufw-user-input -p tcp -m tcp --dport 22 -m state --state NEW -m recent --update --seconds 30 --hitcount 6 --name DEFAULT --mask 255.255.255.255 --rsource -j ufw-user-limit
-A ufw-user-input -p tcp -m tcp --dport 22 -j ufw-user-limit-accept
-A ufw-user-input -p udp -m udp --dport 22 -m state --state NEW -m recent --set --name DEFAULT --mask 255.255.255.255 --rsource
-A ufw-user-input -p udp -m udp --dport 22 -m state --state NEW -m recent --update --seconds 30 --hitcount 6 --name DEFAULT --mask 255.255.255.255 --rsource -j ufw-user-limit
-A ufw-user-input -p udp -m udp --dport 22 -j ufw-user-limit-accept
-A ufw-user-input -p tcp -m tcp --dport 80 -j ACCEPT
-A ufw-user-input -p tcp -m tcp --dport 443 -j ACCEPT
-A ufw-user-input -p udp -m udp --dport 443 -j ACCEPT
-A ufw-user-input -p tcp -m tcp --dport 6789 -j DROP
-A ufw-user-input -p udp -m udp --dport 6789 -j DROP
-A ufw-user-limit -m limit --limit 3/min -j LOG --log-prefix "[UFW LIMIT BLOCK] "
-A ufw-user-limit -j REJECT --reject-with icmp-port-unreachable
-A ufw-user-limit-accept -j ACCEPT
COMMIT
# Completed on Mon Jun 5 20:44:01 2017
答案1
使用以下命令检查 UFW 默认规则
sudo ufw status verbose
您可能会发现流量设置为：Default: deny (outgoing)
如果是这种情况，请在运行以下命令后测试发送电子邮件：
sudo ufw default allow outgoing