NFQUEUE does not let the packet continue where it was processed, but inserts it back into iptables at the start. That is why we need an extra IPSBYPASS chain which has the following tasks:
* Make the BYPASS bit permanent for the entire connection * Clear the REPEAT bit
The latter is more of cosmetic nature so that we can identify packets that have come from suricata again and those which have bypassed the IPS straight away.
The IPS_* chain will now only be sent traffic to, when none of the two relevant bits has been set. Otherwise the packet has already been processed by suricata in the first pass or suricata has decided to bypass the connection.
This massively reduces load on the IPS which allows many common connections (TLS connections with downloads) to bypass the IPS bringing us back to line speed.
Signed-off-by: Michael Tremer michael.tremer@ipfire.org --- src/initscripts/system/firewall | 23 ++++++++++++++++++++--- src/initscripts/system/suricata | 27 +++------------------------ 2 files changed, 23 insertions(+), 27 deletions(-)
diff --git a/src/initscripts/system/firewall b/src/initscripts/system/firewall index ce428393d..530e8f1d6 100644 --- a/src/initscripts/system/firewall +++ b/src/initscripts/system/firewall @@ -17,6 +17,11 @@ NAT_MASK="0x0f000000" IPSEC_MARK="0x00800000" IPSEC_MASK="${IPSEC_MARK}"
+IPS_REPEAT_MARK="0x80000000" +IPS_REPEAT_MASK="0x80000000" +IPS_BYPASS_MARK="0x40000000" +IPS_BYPASS_MASK="0x40000000" + function iptables() { /sbin/iptables --wait "$@" } @@ -41,6 +46,17 @@ iptables_init() { modprobe nf_log_ipv4 sysctl -q -w net.netfilter.nf_log.2=nf_log_ipv4
+ # IPS Bypass Chain which stores the BYPASS bit in connection tracking + iptables -N IPSBYPASS + iptables -A IPSBYPASS -j MARK --set-xmark "0/$(( IPS_REPEAT_MASK ))" + iptables -A IPSBYPASS -j CONNMARK --save-mark + + # Jump into bypass chain when the BYPASS bit is set + for chain in INPUT FORWARD OUTPUT; do + iptables -A "${chain}" -m mark \ + --mark "$(( IPS_REPEAT_MARK | IPS_BYPASS_MARK ))/$(( IPS_REPEAT_MASK | IPS_BYPASS_MASK ))" -j IPSBYPASS + done + # Empty LOG_DROP and LOG_REJECT chains iptables -N LOG_DROP iptables -A LOG_DROP -m limit --limit 10/second -j LOG @@ -147,9 +163,10 @@ iptables_init() { iptables -N IPS_INPUT iptables -N IPS_FORWARD iptables -N IPS_OUTPUT - iptables -A INPUT -j IPS_INPUT - iptables -A FORWARD -j IPS_FORWARD - iptables -A OUTPUT -j IPS_OUTPUT + + for chain in INPUT FORWARD OUTPUT; do + iptables -A "${chain}" -m mark --mark "0x0/$(( IPS_REPEAT_MASK | IPS_BYPASS_MASK ))" -j "IPS_${chain}" + done
# OpenVPN transfer network translation iptables -t nat -N OVPNNAT diff --git a/src/initscripts/system/suricata b/src/initscripts/system/suricata index 72d01b91d..13fcc7f34 100644 --- a/src/initscripts/system/suricata +++ b/src/initscripts/system/suricata @@ -34,12 +34,6 @@ network_zones=( red green blue orange ovpn ) # Array to store the network zones weather the IPS is enabled for. enabled_ips_zones=()
-# Mark and Mask options. -REPEAT_MARK="0x80000000" -REPEAT_MASK="0x80000000" -BYPASS_MARK="0x40000000" -BYPASS_MASK="0x40000000" - # PID file of suricata. PID_FILE="/var/run/suricata.pid"
@@ -134,34 +128,19 @@ function generate_fw_rules { # Flush the firewall chains. flush_fw_chain
- # Skip anything that has the bypass bit set - local chain - for chain in "${IPS_INPUT_CHAIN}" "${IPS_FORWARD_CHAIN}" "${IPS_OUTPUT_CHAIN}"; do - iptables -w -A "${chain}" -m mark --mark "${BYPASS_MARK}/${BYPASS_MASK}" -j RETURN - done - # Check if the array of enabled_ips_zones contains any elements. if [[ ${enabled_ips_zones[@]} ]]; then # Loop through the array and create firewall rules. for enabled_ips_zone in "${enabled_ips_zones[@]}"; do # Create rules queue input and output related traffic and pass it to the IPS. - iptables -w -A "$IPS_INPUT_CHAIN" -i "$enabled_ips_zone" -m mark ! --mark "${REPEAT_MARK}/${REPEAT_MASK}" -j NFQUEUE $NFQ_OPTIONS - iptables -w -A "$IPS_OUTPUT_CHAIN" -o "$enabled_ips_zone" -m mark ! --mark "${REPEAT_MARK}/${REPEAT_MASK}" -j NFQUEUE $NFQ_OPTIONS + iptables -w -A "$IPS_INPUT_CHAIN" -i "$enabled_ips_zone" -j NFQUEUE $NFQ_OPTIONS + iptables -w -A "$IPS_OUTPUT_CHAIN" -o "$enabled_ips_zone" -j NFQUEUE $NFQ_OPTIONS
# Create rules which are required to handle forwarded traffic. for enabled_ips_zone_forward in "${enabled_ips_zones[@]}"; do - iptables -w -A "$IPS_FORWARD_CHAIN" -i "$enabled_ips_zone" -o "$enabled_ips_zone_forward" -m mark ! --mark "${REPEAT_MARK}/${REPEAT_MASK}" -j NFQUEUE $NFQ_OPTIONS + iptables -w -A "$IPS_FORWARD_CHAIN" -i "$enabled_ips_zone" -o "$enabled_ips_zone_forward" -j NFQUEUE $NFQ_OPTIONS done done - - # Add common rules at the end of the chain - for chain in "${IPS_INPUT_CHAIN}" "${IPS_FORWARD_CHAIN}" "${IPS_OUTPUT_CHAIN}"; do - # Clear repeat bit - iptables -w -A "${chain}" -j MARK --set-xmark "0x0/${REPEAT_MASK}" - - # Store bypass bit in CONNMARK - iptables -w -A "${chain}" -m mark --mark "${BYPASS_MARK}/${BYPASS_MASK}" -j CONNMARK --save-mark - done fi }