From 7ea3baad594b889f6f7f4e7e4ccc4dc7c0099bc6 Mon Sep 17 00:00:00 2001 From: Guilhem Moulin Date: Wed, 14 Dec 2022 12:01:33 +0100 Subject: Improve Debian 11's fail2ban rules. --- .../files/etc/fail2ban/action.d/nftables-allports.local | 6 +++--- roles/common/files/etc/fail2ban/fail2ban.local | 11 ----------- .../files/etc/logcheck/ignore.d.server/common-local | 2 ++ .../etc/systemd/system/fail2ban.service.d/override.conf | 5 ++++- roles/common/tasks/fail2ban.yml | 16 ---------------- roles/common/templates/etc/fail2ban/jail.local.j2 | 4 +++- roles/common/templates/etc/nftables.conf.j2 | 6 +++--- 7 files changed, 15 insertions(+), 35 deletions(-) diff --git a/roles/common/files/etc/fail2ban/action.d/nftables-allports.local b/roles/common/files/etc/fail2ban/action.d/nftables-allports.local index 3c8c030..3b9ebc8 100644 --- a/roles/common/files/etc/fail2ban/action.d/nftables-allports.local +++ b/roles/common/files/etc/fail2ban/action.d/nftables-allports.local @@ -9,8 +9,8 @@ actionunban = [Init] # With banaction = *-allports there is no need for separate rule names -set_name = fail2ban -blocktype = drop +table = filter +addr_set = fail2ban [Init?family=inet6] -set_name = fail2ban6 +addr_set = fail2ban6 diff --git a/roles/common/files/etc/fail2ban/fail2ban.local b/roles/common/files/etc/fail2ban/fail2ban.local index 53cba35..23a92e9 100644 --- a/roles/common/files/etc/fail2ban/fail2ban.local +++ b/roles/common/files/etc/fail2ban/fail2ban.local @@ -1,16 +1,5 @@ [Definition] -# Option: logtarget -# Notes.: Set the log target. This could be a file, SYSLOG, STDERR or STDOUT. -# Only one log target can be specified. -# If you change logtarget from the default value and you are -# using logrotate -- also adjust or disable rotation in the -# corresponding configuration file -# (e.g. /etc/logrotate.d/fail2ban on Debian systems) -# Values: [ STDOUT | STDERR | SYSLOG | SYSOUT | FILE ] Default: STDERR -# -logtarget = /var/log/fail2ban/fail2ban.log - # Options: dbfile # Notes.: Set the file for the fail2ban persistent data to be stored. # A value of ":memory:" means database is only stored in memory diff --git a/roles/common/files/etc/logcheck/ignore.d.server/common-local b/roles/common/files/etc/logcheck/ignore.d.server/common-local index b626946..9b0d0fe 100644 --- a/roles/common/files/etc/logcheck/ignore.d.server/common-local +++ b/roles/common/files/etc/logcheck/ignore.d.server/common-local @@ -79,6 +79,8 @@ no matching cipher found: client [.@[:alnum:]-]+(,[.@[:alnum:]-]+)* server [.@[: ^\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ smartd\[[0-9]+\]: Device: /dev/sd[a-z] \[SAT\], CHECK POWER STATUS spins up disk \(0x[0-9a-f]{2} -> 0xff\)$ ^\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ ansible-([_a-z0-9.]+|): Invoked with ^\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ python3\[[0-9]+\]: ansible-[_a-z0-9.]+ Invoked with +^\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ fail2ban-server\[[0-9]+\]: fail2ban\.filter\s*\[[0-9]+\]: INFO\s+\[[._[:alnum:]-]+\] Found [[:xdigit:].:]{3,39} - +^\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ fail2ban-server\[[0-9]+\]: fail2ban\.actions\s*\[[0-9]+\]: NOTICE\s+\[sshd\] (Ban|Unban) [[:xdigit:].:]{3,39} ^\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ sympa_msg\[[0-9]+\]: notice Sympa::Request::Message:: ^\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ sympa_msg\[[0-9]+\]: notice Sympa::(Bulk|Spool)::store\(\) ^\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ sympa_msg\[[0-9]+\]: info Sympa::Spool::_create\(\) Creating directory /var/spool/sympa/auth diff --git a/roles/common/files/etc/systemd/system/fail2ban.service.d/override.conf b/roles/common/files/etc/systemd/system/fail2ban.service.d/override.conf index e3e651f..b34d130 100644 --- a/roles/common/files/etc/systemd/system/fail2ban.service.d/override.conf +++ b/roles/common/files/etc/systemd/system/fail2ban.service.d/override.conf @@ -2,13 +2,16 @@ After=nftables.service [Service] +ExecStartPre= +ExecStart= +ExecStart=/usr/bin/fail2ban-server -xf --logtarget=sysout start + # Need explicit rights to read logs as we don't grant CAP_DAC_READ_SEARCH SupplementaryGroups=adm # Hardening NoNewPrivileges=yes ProtectSystem=strict -ReadWriteDirectories=/var/log/fail2ban RuntimeDirectory=fail2ban PrivateDevices=yes ProtectControlGroups=yes diff --git a/roles/common/tasks/fail2ban.yml b/roles/common/tasks/fail2ban.yml index e56deaf..563075f 100644 --- a/roles/common/tasks/fail2ban.yml +++ b/roles/common/tasks/fail2ban.yml @@ -1,22 +1,6 @@ - name: Install fail2ban apt: pkg=fail2ban -# Log into a dedicate directory so we can use ReadWriteDirectories in -# the .service file -- name: Create directory /var/log/fail2ban - file: path=/var/log/fail2ban - state=directory - owner=root group=adm - mode=0750 - -- name: Fix fail2ban logrotate snippet - lineinfile: dest=/etc/logrotate.d/fail2ban - state=present - line="/var/log/fail2ban/*.log" - insertbefore="^[^#]*\\s{$" - tags: - - logrotate - - name: Configure fail2ban (fail2ban.local) copy: src=etc/fail2ban/fail2ban.local dest=/etc/fail2ban/fail2ban.local diff --git a/roles/common/templates/etc/fail2ban/jail.local.j2 b/roles/common/templates/etc/fail2ban/jail.local.j2 index b01709a..3cd19cc 100644 --- a/roles/common/templates/etc/fail2ban/jail.local.j2 +++ b/roles/common/templates/etc/fail2ban/jail.local.j2 @@ -13,7 +13,9 @@ destemail = admin@fripost.org ignoreip = 127.0.0.0/8, ::1, {{ ipsec_subnet }} banaction = nftables-allports -logpath = /var/log/fail2ban/fail2ban.log + +# must match nftables.conf's blackholes timeouts +bantime = 10m # # JAILS diff --git a/roles/common/templates/etc/nftables.conf.j2 b/roles/common/templates/etc/nftables.conf.j2 index 66b1f9d..805d1a8 100755 --- a/roles/common/templates/etc/nftables.conf.j2 +++ b/roles/common/templates/etc/nftables.conf.j2 @@ -145,7 +145,7 @@ table inet raw { } table inet filter { - # blackholes + # blackholes (timeout must match /etc/fail2ban/jail.local) set fail2ban { type ipv4_addr; timeout 10m; } set fail2ban6 { type ipv6_addr; timeout 10m; } @@ -186,8 +186,8 @@ table inet filter { ip6 version 6 udp sport 547 udp dport 546 ct state related,established accept {% endif %} - meta l4proto tcp ip saddr @fail2ban counter drop - meta l4proto tcp ip6 saddr @fail2ban6 counter drop + ip saddr @fail2ban counter drop + ip6 saddr @fail2ban6 counter drop tcp dport $in-tcp-ports ct state related,established accept tcp dport $in-tcp-ports ct state new counter accept -- cgit v1.2.3