Improve Debian 11's fail2ban rules.

2 files changed, 6 insertions, 4 deletions

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
@@ -1,36 +1,38 @@
 # {{ ansible_managed }}
 # Do NOT edit this file directly!
 
 [DEFAULT]
 
 # Destination email address used solely for the interpolations in
 # jail.{conf,local} configuration files.
 destemail = admin@fripost.org
 
 # "ignoreip" can be a list of IP addresses, CIDR masks or DNS hosts. Fail2ban
 # will not ban a host which matches an address in this list. Several addresses
 # can be defined using space (and/or comma) separator.
 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
 #
 
 [sshd]
 enabled = true
 
 [postfix]
 enabled = {{ 'MX' in group_names }}
 
 [dovecot]
 enabled = {{ 'IMAP' in group_names }}
 
 [postfix-sasl]
 enabled  = {{ 'MSA' in group_names }}
 
 [roundcube-auth]
 enabled = {{ 'webmail' in group_names }}
 logpath = /var/log/roundcube/errors.log
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
@@ -128,83 +128,83 @@ table inet raw {
 
         # stateless filter for bogus TCP packets
         tcp flags & (fin|syn|rst|psh|ack|urg) == 0x0 counter drop # null packet
         tcp flags & (fin|psh|urg) == fin|psh|urg     counter drop # XMAS packet
         tcp flags & (syn|rst) == syn|rst             counter drop
         tcp flags & (fin|rst) == fin|rst             counter drop
         tcp flags & (fin|syn) == fin|syn             counter drop
         tcp flags & (fin|psh|ack) == fin|psh         counter drop
     }
 
     chain PREROUTING {
         type filter hook prerouting priority -199 # > NF_IP_PRI_CONNTRACK (-200)
         policy accept
 
         # stateful filter
         ct state invalid counter drop
     }
 }
 
 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; }
 
     chain input {
         type filter hook input priority 0
         policy drop
 
         iif lo accept
 
         # XXX Bullseye: this is a rather crude match as nftables 0.9.0 lacks support for ipsec expressions
         # to match match inbound resp. outbound policies and source resp. destination tunnel addresses.
         # https://serverfault.com/questions/971735/how-to-match-reqid-in-nftables
         # https://blog.fraggod.net/2016/09/25/nftables-re-injected-ipsec-matching-without-xt_policy.html
         # (We can't use marks to match post-ESP decapsulation here because that doesn't work well with UDP
         # encapsulation.)  We'll also pin the reqid to the lowest address byte in ipsec.conf(5); that way
         # peers can't impersonate each other.
         meta l4proto esp accept
         # ip saddr {{ ipsec_subnet }} ip daddr {{ ipsec[inventory_hostname_short] }} ipsec in reqid $i accept
         ip saddr {{ ipsec_subnet }} ip daddr {{ ipsec[inventory_hostname_short] }} meta secpath exists accept
 
         # incoming ICMP/ICMPv6 traffic was filtered in the ingress chain already
         meta l4proto { icmp, icmpv6 } counter accept
 
         # NTP (ntpd uses sport 123 but systemd-timesyncd does not)
         udp sport 123 ct state related,established accept
 
 {% if groups.all | length > 1 %}
         udp sport  500 udp dport  500 ct state new,related,established accept
 {% if groups.NATed | length > 0 %}
         udp sport 4500 udp dport 4500 ct state new,related,established accept
 {% endif %}
 {% endif %}
 
         udp sport 53 ct state related,established accept
         tcp sport 53 ct state related,established accept
 {% if 'dhclient' in group_names %}
         ip  version 4 udp sport  67 udp dport  68 ct state related,established accept
         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
         tcp sport $out-tcp-ports ct state related,established accept
     }
 
     chain output {
         type filter hook output priority 0
         policy drop
 
         oif lo accept
 
         # XXX Bullseye: unlike for input we can't use marks or test for
         # secpath existence here, because by the time we see a packet to
         # 172.16.0.0/24 we don't know if it'll be encapsulated
         meta l4proto esp accept
         # ip saddr {{ ipsec[inventory_hostname_short] }} ip daddr {{ ipsec_subnet }} ipsec out reqid $i accept
         ip saddr {{ ipsec[inventory_hostname_short] }} ip daddr {{ ipsec_subnet }} accept
 
         meta l4proto { icmp, icmpv6 } counter accept