DROPポリシーにもかかわらずUFWがブロックされない

Question

Ubuntu 16.04では、ufwをインストールし、次のステータス（Sudo ufw status verbose）になるように構成しました。

Status: active Logging: on (full) Default: deny (incoming), allow (outgoing), deny (routed) New profiles: skip To Action From -- ------ ---- 80,443/tcp (Nginx Full) ALLOW IN Anywhere 995/tcp (Dovecot Secure POP3) ALLOW IN Anywhere 993/tcp (Dovecot Secure IMAP) ALLOW IN Anywhere 22/tcp (OpenSSH) ALLOW IN Anywhere 25/tcp (Postfix) ALLOW IN Anywhere 465/tcp (Postfix SMTPS) ALLOW IN Anywhere 9522/tcp (hinext) ALLOW IN Anywhere 9522,9523/tcp (hinext) ALLOW IN Anywhere 9524/tcp (test) ALLOW IN Anywhere 9522/tcp (hinext (v6)) ALLOW IN Anywhere (v6) 9522,9523/tcp (hinext (v6)) ALLOW IN Anywhere (v6) 9524/tcp (test (v6)) ALLOW IN Anywhere (v6)

ご覧のように、ポート8822はリストに含まれていないため、デフォルトポリシー（denyチェーンのincoming）によってブロックする必要があります。

ただし、ポート22および8822でリッスンしているSSHサーバーへの外部からのポート8822へのSSH接続を開くことができます。

ポート8822へのトラフィックがドロップされずにufwファイアウォールを通過できるのはなぜですか？

診断情報の詳細については、iptables-save -cが次のように述べています。

# Generated by iptables-save v1.6.0 on Tue Apr 24 23:55:19 2018 *raw :PREROUTING ACCEPT [622500:111511726] :OUTPUT ACCEPT [631989:135819596] COMMIT # Completed on Tue Apr 24 23:55:19 2018 # Generated by iptables-save v1.6.0 on Tue Apr 24 23:55:19 2018 *mangle :PREROUTING ACCEPT [622500:111511726] :INPUT ACCEPT [622500:111511726] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [631989:135819596] :POSTROUTING ACCEPT [631989:135819596] COMMIT # Completed on Tue Apr 24 23:55:19 2018 # Generated by iptables-save v1.6.0 on Tue Apr 24 23:55:19 2018 *nat :PREROUTING ACCEPT [46994:2923568] :POSTROUTING ACCEPT [7607:511281] :OUTPUT ACCEPT [7607:511281] COMMIT # Completed on Tue Apr 24 23:55:19 2018 # Generated by iptables-save v1.6.0 on Tue Apr 24 23:55:19 2018 *filter :INPUT ACCEPT [63:5355] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] :VZ_FORWARD - [0:0] :VZ_INPUT - [0:0] :VZ_OUTPUT - [0:0] :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-forward - [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] [622500:111511726] -A INPUT -j VZ_INPUT [491972:96179570] -A INPUT -j ufw-before-logging-input [491972:96179570] -A INPUT -j ufw-before-input [21445:1425920] -A INPUT -j ufw-after-input [17022:1199401] -A INPUT -j ufw-after-logging-input [17022:1199401] -A INPUT -j ufw-reject-input [17022:1199401] -A INPUT -j ufw-track-input [0:0] -A FORWARD -j VZ_FORWARD [0:0] -A FORWARD -j ufw-before-logging-forward [0:0] -A FORWARD -j ufw-before-forward [0:0] -A FORWARD -j ufw-after-forward [0:0] -A FORWARD -j ufw-after-logging-forward [0:0] -A FORWARD -j ufw-reject-forward [0:0] -A FORWARD -j ufw-track-forward [631989:135819596] -A OUTPUT -j VZ_OUTPUT [478124:111192792] -A OUTPUT -j ufw-before-logging-output [478124:111192792] -A OUTPUT -j ufw-before-output [4466:322671] -A OUTPUT -j ufw-after-output [4466:322671] -A OUTPUT -j ufw-after-logging-output [4466:322671] -A OUTPUT -j ufw-reject-output [4466:322671] -A OUTPUT -j ufw-track-output [23:1823] -A VZ_INPUT -p tcp -m tcp --dport 80 -j ACCEPT [5136:565736] -A VZ_INPUT -p tcp -m tcp --dport 22 -j ACCEPT [4:172] -A VZ_INPUT -p tcp -m tcp --dport 25 -j ACCEPT [4:172] -A VZ_INPUT -p tcp -m tcp --dport 110 -j ACCEPT [6:304] -A VZ_INPUT -p tcp -m tcp --dport 53 -j ACCEPT [2:115] -A VZ_INPUT -p udp -m udp --dport 53 -j ACCEPT [410:19580] -A VZ_INPUT -p tcp -m tcp --dport 32768:65535 -j ACCEPT [39:3651] -A VZ_INPUT -p udp -m udp --dport 32768:65535 -j ACCEPT [1:44] -A VZ_INPUT -p tcp -m tcp --dport 8880 -j ACCEPT [3:152] -A VZ_INPUT -p tcp -m tcp --dport 8443 -j ACCEPT [8:470] -A VZ_INPUT -s 127.0.0.1/32 -d 127.0.0.1/32 -p tcp -j ACCEPT [0:0] -A VZ_INPUT -s 127.0.0.1/32 -d 127.0.0.1/32 -p udp -j ACCEPT [17:2105] -A VZ_OUTPUT -p tcp -m tcp --sport 80 -j ACCEPT [4940:995587] -A VZ_OUTPUT -p tcp -m tcp --sport 22 -j ACCEPT [4:214] -A VZ_OUTPUT -p tcp -m tcp --sport 25 -j ACCEPT [4:192] -A VZ_OUTPUT -p tcp -m tcp --sport 110 -j ACCEPT [6:240] -A VZ_OUTPUT -p tcp -m tcp --sport 53 -j ACCEPT [0:0] -A VZ_OUTPUT -p udp -m udp --sport 53 -j ACCEPT [3888:279384] -A VZ_OUTPUT -p tcp -j ACCEPT [39:2831] -A VZ_OUTPUT -p udp -j ACCEPT [0:0] -A VZ_OUTPUT -p tcp -m tcp --sport 8880 -j ACCEPT [0:0] -A VZ_OUTPUT -p tcp -m tcp --sport 8443 -j ACCEPT [0:0] -A VZ_OUTPUT -s 127.0.0.1/32 -d 127.0.0.1/32 -p tcp -j ACCEPT [0:0] -A VZ_OUTPUT -s 127.0.0.1/32 -d 127.0.0.1/32 -p udp -j ACCEPT [5:391] -A ufw-after-input -p udp -m udp --dport 137 -j ufw-skip-to-policy-input [0:0] -A ufw-after-input -p udp -m udp --dport 138 -j ufw-skip-to-policy-input [16:700] -A ufw-after-input -p tcp -m tcp --dport 139 -j ufw-skip-to-policy-input [1936:99244] -A ufw-after-input -p tcp -m tcp --dport 445 -j ufw-skip-to-policy-input [0:0] -A ufw-after-input -p udp -m udp --dport 67 -j ufw-skip-to-policy-input [0:0] -A ufw-after-input -p udp -m udp --dport 68 -j ufw-skip-to-policy-input [0:0] -A ufw-after-input -m addrtype --dst-type BROADCAST -j ufw-skip-to-policy-input [0:0] -A ufw-after-logging-forward -j LOG --log-prefix "[UFW BLOCK] " [63:5355] -A ufw-after-logging-input -j LOG --log-prefix "[UFW BLOCK] " [0:0] -A ufw-after-logging-output -j LOG --log-prefix "[UFW ALLOW] " [0:0] -A ufw-before-forward -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT [0:0] -A ufw-before-forward -p icmp -m icmp --icmp-type 3 -j ACCEPT [0:0] -A ufw-before-forward -p icmp -m icmp --icmp-type 4 -j ACCEPT [0:0] -A ufw-before-forward -p icmp -m icmp --icmp-type 11 -j ACCEPT [0:0] -A ufw-before-forward -p icmp -m icmp --icmp-type 12 -j ACCEPT [0:0] -A ufw-before-forward -p icmp -m icmp --icmp-type 8 -j ACCEPT [0:0] -A ufw-before-forward -j ufw-user-forward [10789:9641505] -A ufw-before-input -i lo -j ACCEPT [252164:53646696] -A ufw-before-input -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT [3048:131944] -A ufw-before-input -m conntrack --ctstate INVALID -j ufw-logging-deny [3048:131944] -A ufw-before-input -m conntrack --ctstate INVALID -j DROP [0:0] -A ufw-before-input -p icmp -m icmp --icmp-type 3 -j ACCEPT [0:0] -A ufw-before-input -p icmp -m icmp --icmp-type 4 -j ACCEPT [0:0] -A ufw-before-input -p icmp -m icmp --icmp-type 11 -j ACCEPT [0:0] -A ufw-before-input -p icmp -m icmp --icmp-type 12 -j ACCEPT [21:952] -A ufw-before-input -p icmp -m icmp --icmp-type 8 -j ACCEPT [0:0] -A ufw-before-input -p udp -m udp --sport 67 --dport 68 -j ACCEPT [22062:1348553] -A ufw-before-input -j ufw-not-local [0:0] -A ufw-before-input -d 224.0.0.251/32 -p udp -m udp --dport 5353 -j ACCEPT [0:0] -A ufw-before-input -d 239.255.255.250/32 -p udp -m udp --dport 1900 -j ACCEPT [22062:1348553] -A ufw-before-input -j ufw-user-input [0:0] -A ufw-before-logging-forward -j LOG --log-prefix "[UFW AUDIT] " [327:39433] -A ufw-before-logging-input -j LOG --log-prefix "[UFW AUDIT] " [10:3444] -A ufw-before-logging-output -j LOG --log-prefix "[UFW AUDIT] " [10789:9641505] -A ufw-before-output -o lo -j ACCEPT [277561:60253281] -A ufw-before-output -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT [1888:133952] -A ufw-before-output -j ufw-user-output [0:0] -A ufw-logging-allow -j LOG --log-prefix "[UFW ALLOW] " [29:1244] -A ufw-logging-deny -m conntrack --ctstate INVALID -j LOG --log-prefix "[UFW AUDIT INVALID] " [29:1244] -A ufw-logging-deny -j LOG --log-prefix "[UFW BLOCK] " [22062:1348553] -A ufw-not-local -m addrtype --dst-type LOCAL -j RETURN [0:0] -A ufw-not-local -m addrtype --dst-type MULTICAST -j RETURN [0:0] -A ufw-not-local -m addrtype --dst-type BROADCAST -j RETURN [0:0] -A ufw-not-local -m limit --limit 3/min --limit-burst 10 -j ufw-logging-deny [0:0] -A ufw-not-local -j DROP [0:0] -A ufw-skip-to-policy-forward -j DROP [1957:100335] -A ufw-skip-to-policy-input -j DROP [0:0] -A ufw-skip-to-policy-output -j ACCEPT [1:60] -A ufw-track-output -p tcp -m conntrack --ctstate NEW -j ACCEPT [1746:126492] -A ufw-track-output -p udp -m conntrack --ctstate NEW -j ACCEPT [526:29104] -A ufw-user-input -p tcp -m multiport --dports 80,443 -m comment --comment "\'dapp_Nginx%20Full\'" -j ACCEPT [76:3832] -A ufw-user-input -p tcp -m tcp --dport 995 -m comment --comment "\'dapp_Dovecot%20Secure%20POP3\'" -j ACCEPT [8:372] -A ufw-user-input -p tcp -m tcp --dport 993 -m comment --comment "\'dapp_Dovecot%20Secure%20IMAP\'" -j ACCEPT [9724:581800] -A ufw-user-input -p tcp -m tcp --dport 22 -m comment --comment "\'dapp_OpenSSH\'" -j ACCEPT [61:3500] -A ufw-user-input -p tcp -m tcp --dport 25 -m comment --comment "\'dapp_Postfix\'" -j ACCEPT [10:456] -A ufw-user-input -p tcp -m tcp --dport 465 -m comment --comment "\'dapp_Postfix%20SMTPS\'" -j ACCEPT [0:0] -A ufw-user-input -p tcp -m tcp --dport 9522 -m comment --comment "\'dapp_hinext\'" -j ACCEPT [1:52] -A ufw-user-input -p tcp -m multiport --dports 9522,9523 -m comment --comment "\'dapp_hinext\'" -j ACCEPT [5:256] -A ufw-user-input -p tcp -m tcp --dport 9524 -m comment --comment "\'dapp_test\'" -j ACCEPT [0:0] -A ufw-user-limit -m limit --limit 3/min -j LOG --log-prefix "[UFW LIMIT BLOCK] " [0:0] -A ufw-user-limit -j REJECT --reject-with icmp-port-unreachable [0:0] -A ufw-user-limit-accept -j ACCEPT COMMIT # Completed on Tue Apr 24 23:55:19 2018

andimeier · Answer

Sudo service ufw restartでファイアウォールを再起動しました。その後、ポート8822はuswによってブロックされました-あるはずです。

さらに、iptables-saveも希望するストーリーを教えてくれます：この抜粋をご覧ください：

*filter :INPUT DROP [6:320] :FORWARD DROP [0:0] :OUTPUT ACCEPT [0:0]

「DROP」デフォルトポリシーに注意してください。最初の投稿では、「ACCEPT」デフォルトポリシーに気付きましたが、理解できませんでした。

したがって、ufwを再起動することで問題が解決したようです。