Тема: Надеждност на iptables? (Прочетена 6824 пъти)

angie_bg · « -: Sep 08, 2016, 11:05 »

Здравейте, доколко надеждно е блокирането на външни заявки с iptables? Ситуацията е следната:
В ufw съм блокирал всичко от адреси 116.16.0.0 /12

Цитат

$ sudo ufw status numbered | grep 116
[ 1] Anywhere DENY IN 116.16.0.0/12

Съответното правило (2) в iptables е:

Цитат

$ sudo iptables -L | grep 116
DROP all -- 116.31.116.51 anywhere
DROP all -- 116.16.0.0/12 anywhere

Маската 12 трябва да покрива адресите 116.16.0.0 - 116.31.255.255:

Цитат

$ sudo whois 116.16.0.0/12
% [whois.apnic.net]
% Whois data copyright terms http://www.apnic.net/db/dbcopyright.html

% Information related to '116.16.0.0 - 116.31.255.255'

inetnum: 116.16.0.0 - 116.31.255.255
netname: CHINANET-GD
descr: CHINANET Guangdong province network
descr: China Telecom
descr: No.31,jingrong street
descr: Beijing 100032
country: CN
admin-c: CH93-AP
tech-c: IC83-AP
mnt-by: APNIC-HM
mnt-lower: MAINT-CHINANET-GD
mnt-routes: MAINT-CHINANET-GD
status: ALLOCATED PORTABLE
...

Въпреки блокирането на адрес от този диапазон (116.31.116.51) от iptables в 09:56:

Цитат

$ sudo cat /var/log/ufw.log | grep "SRC=116." |tail
...
Sep 8 09:56:15 localhost kernel: [2163845.260896] [UFW BLOCK] IN=eth0 OUT= MAC=00:03:47:62:66:1b:00:17:3f:62:4e:2c:08:00 SRC=116.31.116.51 DST=192.168.1.3 LEN=40 TOS=0x00 PREC=0x00 TTL=42 ID=17876 DF PROTO=TCP SPT=49121 DPT=22 WINDOW=0 RES=0x00 RST URGP=0

в 10:10 той отново е блокиран от fail2ban:

Цитат

$ sudo cat /var/log/fail2ban.log |grep "Ban 116"
...
2016-09-07 15:09:33,978 fail2ban.actions: WARNING [ssh] Ban 116.31.116.51
2016-09-07 16:20:03,830 fail2ban.actions: WARNING [ssh] Ban 116.31.116.51
2016-09-07 18:45:52,513 fail2ban.actions: WARNING [ssh] Ban 116.31.116.51
2016-09-07 19:55:17,292 fail2ban.actions: WARNING [ssh] Ban 116.31.116.51
2016-09-08 00:23:02,900 fail2ban.actions: WARNING [ssh] Ban 116.31.116.51
2016-09-08 02:15:08,732 fail2ban.actions: WARNING [ssh] Ban 116.31.116.51
2016-09-08 03:45:36,210 fail2ban.actions: WARNING [ssh] Ban 116.31.116.51
2016-09-08 10:10:05,415 fail2ban.actions: WARNING [ssh] Ban 116.31.116.51

Как заявките от този адрес се „промъкват“ и защо?

makeme · « **Отговор #1 -:** Sep 08, 2016, 12:01 »

До колкото съм запознат, когато инсталираш и конфигурираш fail2ban заявките за ssh минават през него първо и после ги дропи през айпитаблиците.
Така, че предполагам затова ти излиза в fail2ban лога. Споко, напълно защитен си.

angie_bg · « **Отговор #2 -:** Sep 08, 2016, 12:52 »

Цитат

До колкото съм запознат, когато инсталираш и конфигурираш fail2ban заявките за ssh минават през него първо и после ги дропи през айпитаблиците.
Така, че предполагам затова ти излиза в fail2ban лога.

@Makeme, мисля, че не си напълно прав. Според мен последователността е следната:
заявка -> iptables -> филтрирана заявка -> fail2ban -> нов филтър/правило в iptables.
В моя случай

Цитат

DROP all -- 116.16.0.0/12 anywhere

е филтъра/правилото на iptables, която е „прескочено“ от 116.31.116.51, и след 3 поредни опита за влизане за времето от 09:56 до 10:10 е създадено ново правило, важащо 1 час

Цитат

DROP all -- 116.31.116.51 anywhere

.
Напр. в момента (12:51) е валидно „твърдото“ правило на iptables, като след 10:10 не е правен нов опит да влизане от този адрес (има от други).

makeme · « **Отговор #3 -:** Sep 08, 2016, 13:24 »

Разбира се може и да греша, но съдейки по това -> http://www.the-art-of-web.com/system/fail2ban/ (точка 3), да заявката пристига 1во в iptables, но в "fail2ban-ssh chain" и от там вече, дропи.
И аз ще чакам да се изкаже някой малко по-компетентен по темата, понеже ми е интересно

.
Не съм го ползвал много тоя fail2ban, понеже за брутфорсите към SSh, CSF ми е фаворит.

petar258 · « **Отговор #4 -:** Sep 08, 2016, 15:57 »

По спомени правилото на fail2ban стои най-отгоре и затова минава първо през него. Другия вариант е да имаш някаква грешка. Като си гледаш конфигурацията ползвай iptables -Lv за да видиш повече подробности, и не грепвай само 116, за да видиш всички редове и да ти се изясни картинката. И може да се наложи да ползваш и -t filter към командата.

Demayl · « **Отговор #5 -:** Sep 08, 2016, 16:12 »

Да, трябва да проследиш целия chain. 100% не стига до този rule ( misconfig ). Иначе fail2ban добавя в самото начало на rules и затова винаги работи.

angie_bg · « **Отговор #6 -:** Sep 08, 2016, 17:04 »

15:01

Цитат

$ sudo iptables -L -v
Chain INPUT (policy DROP 2058 packets, 197K bytes)
pkts bytes target prot opt in out source destination
929 51087 fail2ban-proftpd tcp -- any any anywhere anywhere multiport dports ftp,ftp-data,ftps,ftps-data,1234,1233
124K 13M fail2ban-ssh-ddos tcp -- any any anywhere anywhere multiport dports ssh
124K 13M fail2ban-ssh tcp -- any any anywhere anywhere multiport dports ssh
28M 21G ufw-before-logging-input all -- any any anywhere anywhere
28M 21G ufw-before-input all -- any any anywhere anywhere
227K 55M ufw-after-input all -- any any anywhere anywhere
211K 53M ufw-after-logging-input all -- any any anywhere anywhere
211K 53M ufw-reject-input all -- any any anywhere anywhere
211K 53M ufw-track-input all -- any any anywhere anywhere

Chain FORWARD (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 ufw-before-logging-forward all -- any any anywhere anywhere
0 0 ufw-before-forward all -- any any anywhere anywhere
0 0 ufw-after-forward all -- any any anywhere anywhere
0 0 ufw-after-logging-forward all -- any any anywhere anywhere
0 0 ufw-reject-forward all -- any any anywhere anywhere

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
5210K 310M ufw-before-logging-output all -- any any anywhere anywhere
5210K 310M ufw-before-output all -- any any anywhere anywhere
25074 2368K ufw-after-output all -- any any anywhere anywhere
25074 2368K ufw-after-logging-output all -- any any anywhere anywhere
25074 2368K ufw-reject-output all -- any any anywhere anywhere
25074 2368K ufw-track-output all -- any any anywhere anywhere

Chain fail2ban-proftpd (1 references)
pkts bytes target prot opt in out source destination
929 51087 RETURN all -- any any anywhere anywhere

Chain fail2ban-ssh (1 references)
pkts bytes target prot opt in out source destination
89872 10M RETURN all -- any any anywhere anywhere

Chain fail2ban-ssh-ddos (1 references)
pkts bytes target prot opt in out source destination
124K 13M RETURN all -- any any anywhere anywhere

Chain ufw-after-forward (1 references)
pkts bytes target prot opt in out source destination

Chain ufw-after-input (1 references)
pkts bytes target prot opt in out source destination
8453 660K ufw-skip-to-policy-input udp -- any any anywhere anywhere udp dpt:netbios-ns
2383 591K ufw-skip-to-policy-input udp -- any any anywhere anywhere udp dpt:netbios-dgm
11 528 ufw-skip-to-policy-input tcp -- any any anywhere anywhere tcp dpt:netbios-ssn
25 1260 ufw-skip-to-policy-input tcp -- any any anywhere anywhere tcp dpt:microsoft-ds
11 3701 ufw-skip-to-policy-input udp -- any any anywhere anywhere udp dpt:bootps
0 0 ufw-skip-to-policy-input udp -- any any anywhere anywhere udp dpt:bootpc
1990 460K ufw-skip-to-policy-input all -- any any anywhere anywhere ADDRTYPE match dst-type BROADCAST

Chain ufw-after-logging-forward (1 references)
pkts bytes target prot opt in out source destination
0 0 LOG all -- any any anywhere anywhere limit: avg 3/min burst 10 LOG level warning prefix "[UFW BLOCK] "

Chain ufw-after-logging-input (1 references)
pkts bytes target prot opt in out source destination
1318 134K LOG all -- any any anywhere anywhere limit: avg 3/min burst 10 LOG level warning prefix "[UFW BLOCK] "

Chain ufw-after-logging-output (1 references)
pkts bytes target prot opt in out source destination
246 28342 LOG all -- any any anywhere anywhere limit: avg 3/min burst 10 LOG level warning prefix "[UFW ALLOW] "

Chain ufw-after-output (1 references)
pkts bytes target prot opt in out source destination

Chain ufw-before-forward (1 references)
pkts bytes target prot opt in out source destination
0 0 ufw-user-forward all -- any any anywhere anywhere

Chain ufw-before-input (1 references)
pkts bytes target prot opt in out source destination
133 10494 ACCEPT all -- lo any anywhere anywhere
16M 12G ACCEPT all -- any any anywhere anywhere state RELATED,ESTABLISHED
1025 54531 ufw-logging-deny all -- any any anywhere anywhere state INVALID
1025 54531 DROP all -- any any anywhere anywhere state INVALID
0 0 ACCEPT icmp -- any any anywhere anywhere icmp destination-unreachable
0 0 ACCEPT icmp -- any any anywhere anywhere icmp source-quench
0 0 ACCEPT icmp -- any any anywhere anywhere icmp time-exceeded
0 0 ACCEPT icmp -- any any anywhere anywhere icmp parameter-problem
98 3756 ACCEPT icmp -- any any anywhere anywhere icmp echo-request
11 6336 ACCEPT udp -- any any anywhere anywhere udp spt:bootps dpt:bootpc
120K 8694K ufw-not-local all -- any any anywhere anywhere
3307 247K ACCEPT udp -- any any anywhere 224.0.0.251 udp dpt:mdns
0 0 ACCEPT udp -- any any anywhere 239.255.255.250 udp dpt:1900
117K 8447K ufw-user-input all -- any any anywhere anywhere

Chain ufw-before-logging-forward (1 references)
pkts bytes target prot opt in out source destination
0 0 LOG all -- any any anywhere anywhere state NEW limit: avg 3/min burst 10 LOG level warning prefix "[UFW AUDIT] "

Chain ufw-before-logging-input (1 references)
pkts bytes target prot opt in out source destination
1318 150K LOG all -- any any anywhere anywhere state NEW limit: avg 3/min burst 10 LOG level warning prefix "[UFW AUDIT] "

Chain ufw-before-logging-output (1 references)
pkts bytes target prot opt in out source destination
245 28290 LOG all -- any any anywhere anywhere state NEW limit: avg 3/min burst 10 LOG level warning prefix "[UFW AUDIT] "

Chain ufw-before-output (1 references)
pkts bytes target prot opt in out source destination
133 10494 ACCEPT all -- any lo anywhere anywhere
3019K 169M ACCEPT all -- any any anywhere anywhere state RELATED,ESTABLISHED
9514 1002K ufw-user-output all -- any any anywhere anywhere

Chain ufw-logging-allow (0 references)
pkts bytes target prot opt in out source destination
0 0 LOG all -- any any anywhere anywhere limit: avg 3/min burst 10 LOG level warning prefix "[UFW ALLOW] "

Chain ufw-logging-deny (2 references)
pkts bytes target prot opt in out source destination
1 40 LOG all -- any any anywhere anywhere state INVALID limit: avg 3/min burst 10 LOG level warning prefix "[UFW AUDIT INVALID] "
1 40 LOG all -- any any anywhere anywhere limit: avg 3/min burst 10 LOG level warning prefix "[UFW BLOCK] "

Chain ufw-not-local (1 references)
pkts bytes target prot opt in out source destination
72539 6248K RETURN all -- any any anywhere anywhere ADDRTYPE match dst-type LOCAL
42820 1359K RETURN all -- any any anywhere anywhere ADDRTYPE match dst-type MULTICAST
4807 1088K RETURN all -- any any anywhere anywhere ADDRTYPE match dst-type BROADCAST
0 0 ufw-logging-deny all -- any any anywhere anywhere limit: avg 3/min burst 10
0 0 DROP all -- any any anywhere anywhere

Chain ufw-reject-forward (1 references)
pkts bytes target prot opt in out source destination

Chain ufw-reject-input (1 references)
pkts bytes target prot opt in out source destination

Chain ufw-reject-output (1 references)
pkts bytes target prot opt in out source destination

Chain ufw-skip-to-policy-forward (0 references)
pkts bytes target prot opt in out source destination
0 0 DROP all -- any any anywhere anywhere

Chain ufw-skip-to-policy-input (7 references)
pkts bytes target prot opt in out source destination
12873 1716K DROP all -- any any anywhere anywhere

Chain ufw-skip-to-policy-output (0 references)
pkts bytes target prot opt in out source destination
0 0 ACCEPT all -- any any anywhere anywhere

Chain ufw-track-input (1 references)
pkts bytes target prot opt in out source destination

Chain ufw-track-output (1 references)
pkts bytes target prot opt in out source destination
1338 81860 ACCEPT tcp -- any any anywhere anywhere state NEW
8067 913K ACCEPT udp -- any any anywhere anywhere state NEW

Chain ufw-user-forward (1 references)
pkts bytes target prot opt in out source destination

Chain ufw-user-input (1 references)
pkts bytes target prot opt in out source destination
66 4193 DROP all -- any any 116.16.0.0/12 anywhere
0 0 DROP all -- any any 221.192.0.0/14 anywhere
19 1076 ACCEPT tcp -- any any anywhere anywhere tcp dpt:ssh
0 0 ACCEPT udp -- any any anywhere anywhere udp dpt:ssh
19 1012 ACCEPT tcp -- any any anywhere anywhere tcp dpt:http
0 0 ACCEPT udp -- any any anywhere anywhere udp dpt:http
6 296 ACCEPT tcp -- any any anywhere anywhere tcp dpt:https
0 0 ACCEPT udp -- any any anywhere anywhere udp dpt:https
1 60 ACCEPT tcp -- any any anywhere anywhere tcp dpt:1234
1 60 ACCEPT tcp -- any any anywhere anywhere tcp dpt:ftp-data
0 0 ACCEPT tcp -- any any anywhere anywhere tcp dpt:49152
0 0 ACCEPT tcp -- any any anywhere anywhere tcp dpt:65534
1 60 ACCEPT tcp -- any any anywhere anywhere tcp dpt:ftp
0 0 ACCEPT tcp -- any any angie-desktop.local anywhere tcp dpt:webmin
0 0 ACCEPT udp -- any any angie-desktop.local anywhere udp dpt:10000

Chain ufw-user-limit (0 references)
pkts bytes target prot opt in out source destination
0 0 LOG all -- any any anywhere anywhere limit: avg 3/min burst 5 LOG level warning prefix "[UFW LIMIT BLOCK] "
0 0 REJECT all -- any any anywhere anywhere reject-with icmp-port-unreachable

Chain ufw-user-limit-accept (0 references)
pkts bytes target prot opt in out source destination
0 0 ACCEPT all -- any any anywhere anywhere

Chain ufw-user-logging-forward (0 references)
pkts bytes target prot opt in out source destination

Chain ufw-user-logging-input (0 references)
pkts bytes target prot opt in out source destination

Chain ufw-user-logging-output (0 references)
pkts bytes target prot opt in out source destination

Chain ufw-user-output (1 references)
pkts bytes target prot opt in out source destination

Demayl · « **Отговор #7 -:** Sep 08, 2016, 19:14 »

Виж на chain-a ufw-not-local първия rule. Може да пробваш да го махнеш или ако не стане да пробваш някой друг RETURN. Виж и fail2ban-ssh-ddos
Това е на пръв поглед

petar258 · « **Отговор #8 -:** Sep 10, 2016, 22:25 »

Всъщност всичко си работи, но не си редактирал конфига на fail2ban и затова има чести опити. Ако е правилно конфигуриран, няма нужда да добавяш ръчно правила за блокиране. По подразбиране конфига на fail2ban позволява 5 опита и се сваля бан-а след 10 минути. Трябва да се промени на 3 опита и времето за бан да се вдигне поне на 3 дни. Това ще откаже напълно всички мераклии. Тук има едно обяснение за редактиране на конфига, при желание можеш да намериш и други обяснения. А и в самия конфиг има доста подробно обяснение на опциите. http://www.ducea.com/2006/07/03/using-fail2ban-to-block-brute-force-attacks/

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Автор Тема: Надеждност на iptables? (Прочетена 6824 пъти)

angie_bg

Надеждност на iptables?

makeme

Re: Надеждност на iptables?

angie_bg

Re: Надеждност на iptables?

makeme

Re: Надеждност на iptables?

petar258

Re: Надеждност на iptables?

Demayl

Re: Надеждност на iptables?

angie_bg

Re: Надеждност на iptables?

Demayl

Re: Надеждност на iptables?

petar258

Re: Надеждност на iptables?