Fail2ban
How to protect your server from Brute-force attacks and prevent intrusions with Fail2ban
Installation
pacman -Syu firewalld fail2ban ipset
Enable and start services
systemctl enable firewalld
systemctl start firewalld
systemctl enable fail2ban
systemctl start fail2ban
Firewalld configuration
Set the default zone
firewall-cmd --set-default-zone=public
Add an interface to a zone
firewall-cmd --permanent --zone=public --add-interface=enp1s0
Get active zones
firewall-cmd --get-active-zones
Get a list of all supported services
firewall-cmd --get-services
Enable firewalld services in a zone
firewall-cmd --permanent --zone=public --add-service=ssh
firewall-cmd --permanent --zone=public --add-service=http
firewall-cmd --permanent --zone=public --add-service=https
firewall-cmd --permanent --zone=public --add-service=zabbix-agent
firewall-cmd --permanent --zone=public --add-service=smtp
firewall-cmd --reload
firewall-cmd --list-all
firewall-cmd --state
Fail2ban configuration
Copy default fail2ban configuration from “jail.conf” to “jail.local”
cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local
Set default values
/etc/fail2ban/jail.local
[DEFAULT]
ignoreip = 127.0.0.1/8 10.0.0.0/22
bantime = 1w
findtime = 1d
maxretry = 3
backend = auto
action = %(action_)s
[recidive]
enabled = true
logpath = /var/log/fail2ban.log
banaction = %(banaction_allports)s
bantime = -1 ; permanent
findtime = 1d
maxretry = 6
Setup jails
/etc/fail2ban/jail.d/nginx.local
[nginx-noscript]
enabled = true
port = http,https
filter = nginx-noscript
logpath = /var/log/nginx/*access.log
maxretry = 1
bantime = 86400
[nginx-badbots]
enabled = true
port = http,https
filter = nginx-badbots
logpath = /var/log/nginx/*access.log
bantime = 86400
maxretry = 1
[nginx-nohome]
enabled = true
port = http,https
filter = nginx-nohome
logpath = /var/log/nginx/*access.log
bantime = 600
maxretry = 2
[nginx-noproxy]
enabled = true
port = http,https
filter = nginx-noproxy
logpath = /var/log/nginx/*access.log
maxretry = 2
bantime = 86400
[nginx-http-auth]
enabled = true
port = http,https
filter = nginx-http-auth
logpath = /var/log/nginx/*error.log
bantime = 600
maxretry = 6
[nginx-login]
enabled = true
port = http,https
filter = nginx-login
logpath = /var/log/nginx/*access.log
bantime = 600
maxretry = 6
[nginx-limit-req]
enabled = true
filter = nginx-limit-req
port = http,https
logpath = /var/log/nginx/*error.log
bantime = 7200
maxretry = 10
Filter definitions
/etc/fail2ban/filter.d/nginx-badbots.conf
# Fail2Ban configuration file
#
# Regexp to catch known spambots and software alike. Please verify
# that it is your intent to block IPs which were driven by
# above mentioned bots.
[Definition]
badbotscustom = EmailCollector|WebEMailExtrac|TrackBack/1\.02|sogou music spider|(?:Mozilla/\d+\.\d+ )?Jorgee
badbots = Atomic_Email_Hunter/4\.0|atSpider/1\.0|autoemailspider|bwh3_user_agent|China Local Browse 2\.6|ContactBot/0\.2|ContentSmartz|DataCha0s/2\.0|DBrowse 1\.4b|DBrowse 1\.4d|Demo Bot DOT 16b|Demo Bot Z 16b|DSurf15a 01|DSurf15a 71|DSurf15a 81|DSurf15a VA|EBrowse 1\.4b|Educate Search VxB|EmailSiphon|EmailSpider|EmailWolf 1\.00|ESurf15a 15|ExtractorPro|Franklin Locator 1\.8|FSurf15a 01|Full Web Bot 0416B|Full Web Bot 0516B|Full Web Bot 2816B|Guestbook Auto Submitter|Industry Program 1\.0\.x|ISC Systems iRc Search 2\.1|IUPUI Research Bot v 1\.9a|LARBIN-EXPERIMENTAL \(efp@gmx\.net\)|LetsCrawl\.com/1\.0 \+http\://letscrawl\.com/|Lincoln State Web Browser|LMQueueBot/0\.2|LWP\:\:Simple/5\.803|Mac Finder 1\.0\.xx|MFC Foundation Class Library 4\.0|Microsoft URL Control - 6\.00\.8xxx|Missauga Locate 1\.0\.0|Missigua Locator 1\.9|Missouri College Browse|Mizzu Labs 2\.2|Mo College 1\.9|MVAClient|Mozilla/2\.0 \(compatible; NEWT ActiveX; Win32\)|Mozilla/3\.0 \(compatible; Indy Library\)|Mozilla/3\.0 \(compatible; scan4mail \(advanced version\) http\://www\.peterspages\.net/?scan4mail\)|Mozilla/4\.0 \(compatible; Advanced Email Extractor v2\.xx\)|Mozilla/4\.0 \(compatible; Iplexx Spider/1\.0 http\://www\.iplexx\.at\)|Mozilla/4\.0 \(compatible; MSIE 5\.0; Windows NT; DigExt; DTS Agent|Mozilla/4\.0 efp@gmx\.net|Mozilla/5\.0 \(Version\: xxxx Type\:xx\)|NameOfAgent \(CMS Spider\)|NASA Search 1\.0|Nsauditor/1\.x|PBrowse 1\.4b|PEval 1\.4b|Poirot|Port Huron Labs|Production Bot 0116B|Production Bot 2016B|Production Bot DOT 3016B|Program Shareware 1\.0\.2|PSurf15a 11|PSurf15a 51|PSurf15a VA|psycheclone|RSurf15a 41|RSurf15a 51|RSurf15a 81|searchbot admin@google\.com|ShablastBot 1\.0|snap\.com beta crawler v0|Snapbot/1\.0|Snapbot/1\.0 \(Snap Shots, \+http\://www\.snap\.com\)|sogou develop spider|Sogou Orion spider/3\.0\(\+http\://www\.sogou\.com/docs/help/webmasters\.htm#07\)|sogou spider|Sogou web spider/3\.0\(\+http\://www\.sogou\.com/docs/help/webmasters\.htm#07\)|sohu agent|SSurf15a 11 |TSurf15a 11|Under the Rainbow 2\.2|User-Agent\: Mozilla/4\.0 \(compatible; MSIE 6\.0; Windows NT 5\.1\)|VadixBot|WebVulnCrawl\.unknown/1\.0 libwww-perl/5\.803|Wells Search II|WEP Search 00
failregex = ^<HOST> -.*"(GET|POST|HEAD).*HTTP.*"(?:%(badbots)s|%(badbotscustom)s)"$
ignoreregex =
datepattern = ^[^\[]*\[({DATE})
{^LN-BEG}
# DEV Notes:
# List of bad bots fetched from http://www.user-agents.org
# Generated on Thu Nov 7 14:23:35 PST 2013 by files/gen_badbots.
#
# Author: Yaroslav Halchenko
/etc/fail2ban/filter.d/nginx-http-auth.conf
# fail2ban filter configuration for nginx
[Definition]
failregex = ^ \[error\] \d+#\d+: \*\d+ user "(?:[^"]+|.*?)":? (?:password mismatch|was not found in "[^\"]*"), client: <HOST>, server: \S*, request: "\S+ \S+ HTTP/\d+\.\d+", host: "\S+"(?:, referrer: "\S+")?\s*$
^ \[error\] \d+#\d+: \*\d+ no user/password was provided for basic authentication, client: <HOST>, server: \S+, request: "\S+ \S+ HTTP/\d+\.\d+", host: "\S+"\s*$
ignoreregex =
datepattern = {^LN-BEG}
# DEV NOTES:
# Based on samples in https://github.com/fail2ban/fail2ban/pull/43/files
# Extensive search of all nginx auth failures not done yet.
#
# Author: Daniel Black
/etc/fail2ban/filter.d/nginx-limit-req.conf
# Fail2ban filter configuration for nginx :: limit_req
# used to ban hosts, that were failed through nginx by limit request processing rate
#
# Author: Serg G. Brester (sebres)
#
# To use 'nginx-limit-req' filter you should have `ngx_http_limit_req_module`
# and define `limit_req` and `limit_req_zone` as described in nginx documentation
# http://nginx.org/en/docs/http/ngx_http_limit_req_module.html
#
# Example:
#
# http {
# ...
# limit_req_zone $binary_remote_addr zone=lr_zone:10m rate=1r/s;
# ...
# # http, server, or location:
# location ... {
# limit_req zone=lr_zone burst=1 nodelay;
# ...
# }
# ...
# }
# ...
#
[Definition]
# Specify following expression to define exact zones, if you want to ban IPs limited
# from specified zones only.
# Example:
#
# ngx_limit_req_zones = lr_zone|lr_zone2
#
ngx_limit_req_zones = [^"]+
# Use following full expression if you should range limit request to specified
# servers, requests, referrers etc. only :
#
# failregex = ^\s*\[[a-z]+\] \d+#\d+: \*\d+ limiting requests, excess: [\d\.]+ by zone "(?:%(ngx_limit_req_zones)s)", client: <HOST>, server: \S*, request: "\S+ \S+ HTTP/\d+\.\d+", host: "\S+"(, referrer: "\S+")?\s*$
# Shortly, much faster and stable version of regexp:
failregex = ^\s*\[[a-z]+\] \d+#\d+: \*\d+ limiting requests, excess: [\d\.]+ by zone "(?:%(ngx_limit_req_zones)s)", client: <HOST>,
ignoreregex =
datepattern = {^LN-BEG}
/etc/fail2ban/filter.d/nginx-login.conf
# Login filter /etc/fail2ban/filter.d/nginx-login.conf: Blocks IPs that fail to
# authenticate using web application's log in page
#
# Scan access log for HTTP 200 + POST /sessions => failed log in
[Definition]
failregex = ^<HOST> -.*POST /sessions HTTP/1\.." 200
ignoreregex =
/etc/fail2ban/filter.d/nginx-nohome.conf
[Definition]
failregex = ^<HOST> -.*GET .*/~.*
maxlines = 1
[^\]]*)?\] (?:for user (?:"[^"]*" )?)?failed\.\s*$
datepattern = ^%%H:%%M:%%S\.%%f
ignoreregex =
/etc/fail2ban/filter.d/nginx-noproxy.conf
[Definition]
failregex = ^<HOST> -.*GET http.*
ignoreregex =
/etc/fail2ban/filter.d/nginx-noscript.conf
# Noscript filter /etc/fail2ban/filter.d/nginx-noscript.conf:
# Block IPs trying to execute scripts such as .php, .pl, .exe and other funny scripts.
# Matches e.g.
# 192.168.1.1 - - "GET /something.php
[Definition]
failregex = ^<HOST> -.*"GET .*(\.php|\.asp|\.exe|\.pl|\.cgi|\.scgi)[ /\?].*" .*$
ignoreregex = ^<HOST> -.*GET.*(/zabbix.php|/jsLoader.php|https://app.plex.tv/)
Set permissions
chmod 644 /etc/fail2ban/filter.d/nginx-*
systemctl restart fail2ban
fail2ban-client status
fail2ban-client banned
firewall-cmd --list-rich-rules
fail2ban-client get nginx-badbots actions
fail2ban-client unban IPADRESS
/etc/fail2ban/jail.d/00-firewalld.local
[DEFAULT]
banaction = firewallcmd-ipset
Service hardening
Currently, Fail2ban must be run as root. Therefore, you may wish to consider hardening the process with systemd.
/etc/systemd/system/fail2ban.service.d/override.conf
[Service]
PrivateDevices=yes
PrivateTmp=yes
ProtectHome=read-only
ProtectSystem=strict
ReadWritePaths=-/var/run/fail2ban
ReadWritePaths=-/var/lib/fail2ban
ReadWritePaths=-/var/log/fail2ban
ReadWritePaths=-/var/spool/postfix/maildrop
ReadWritePaths=-/run/xtables.lock
CapabilityBoundingSet=CAP_AUDIT_READ CAP_DAC_READ_SEARCH CAP_NET_ADMIN CAP_NET_RAW
The CapabilityBoundingSet parameters CAP_DAC_READ_SEARCH will allow Fail2ban full read access to every directory and file.
CAP_NET_ADMIN and CAP_NET_RAW allow Fail2ban to operate on any firewall that has command-line shell interface.
By using ProtectSystem=strict the filesystem hierarchy will only be read-only,
ReadWritePaths allows Fail2ban to have write access on required paths.
Create /etc/fail2ban/fail2ban.local with the correct logtarget path
/etc/fail2ban/fail2ban.local
[Definition]
logtarget = /var/log/fail2ban/fail2ban.log
Create the /var/log/fail2ban/ directory as root.
mkdir /var/log/fail2ban/
reload systemd daemon to apply the changes of the unit and restart fail2ban.service
Debug filter
fail2ban-regex /var/log/nginx/error.log /etc/fail2ban/filter.d/nginx-http-auth.conf
fail2ban-regex /var/log/nginx/error.log /etc/fail2ban/filter.d/nginx-limit-req.conf
fail2ban-regex /var/log/nginx/access.log /etc/fail2ban/filter.d/nginx-noscript.conf
fail2ban-regex /var/log/nginx/access.log /etc/fail2ban/filter.d/nginx-badbots.conf
fail2ban-regex /var/log/nginx/access.log /etc/fail2ban/filter.d/nginx-nohome.conf
fail2ban-regex /var/log/nginx/access.log /etc/fail2ban/filter.d/nginx-noproxy.conf
fail2ban-regex /var/log/nginx/access.log /etc/fail2ban/filter.d/nginx-login.conf
Check status
fail2ban-client status
fail2ban-client banned
cat /var/log/fail2ban/fail2ban.log
tail -f /var/log/fail2ban/fail2ban.log
Manually ban IP
fail2ban-client -vvv set recidive banip 83.97.73.87
fail2ban-client status recidive
Manually unban IP
fail2ban-client banned
fail2ban-client unban 192.168.0.100