Iptables rules to prevent UDP Outgoing flood

yena

Active Member
Nov 18, 2011
315
2
38
Hello, i have bad experience regarding Outgoing UDP flood.

If i put UDP flood rules on HOST server, they cover also GUEST ( Openvz, LXC, KVM ) VPS ?

My RULES in init.d script:

------------------------------------------------------------------
#!/bin/sh
### BEGIN INIT INFO
# Provides: firewall
# Required-Start: $network $remote_fs $syslog
# Required-Stop:
# Default-Start: S
# Default-Stop:
# Short-Description: Activate iptables.
### END INIT INFO

WAN="eth1"
LAN="eth0"

case "$1" in
start)
echo "STRATING FIREWALL"


PATH='/sbin'

## INIT

# Flush previous rules, delete chains and reset counters
iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT
iptables -t nat -F
iptables -t mangle -F
iptables -F
iptables -X

# Outbound UDP Flood protection in a user defined chain.
/sbin/iptables -N udp-flood
/sbin/iptables -A OUTPUT -p udp -j udp-flood
/sbin/iptables -A udp-flood -p udp -m limit --limit 50/s -j RETURN
/sbin/iptables -A udp-flood -j LOG --log-level 4 --log-prefix 'UDP-flood attempt: '
/sbin/iptables -A udp-flood -j DROP

# allow dns requests to google nameservers
/sbin/iptables -A OUTPUT -p udp --dport 53 -d 8.8.8.8 -j ACCEPT
/sbin/iptables -A OUTPUT -p udp --dport 53 -d 8.8.4.4 -j ACCEPT
/sbin/iptables -A OUTPUT -p udp --dport 53 -d 85.18.200.200 -j ACCEPT
/sbin/iptables -A OUTPUT -p udp --dport 53 -d 89.97.140.140 -j ACCEPT
/sbin/iptables -A OUTPUT -p udp --dport 123 -j ACCEPT

# block all other udp
/sbin/iptables -A OUTPUT -p udp -j DROP
/sbin/ip6tables -A OUTPUT -p udp -j DROP

;;
stop)
echo "Stopping FIREWALL Flush previous rules, delete chains and reset counters"

# Flush previous rules, delete chains and reset counters
iptables -F
iptables -X
iptables -Z
iptables -t nat -F

# Default policies
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT

echo "FIREWALL STOPPED"
iptables -L
iptables -t nat -L -nv

;;
restart)
echo "Restarting Firewall"
/etc/init.d/firewall stop;
/etc/init.d/firewall start;
;;
status)
iptables -L -x -v -n --line-numbers
iptables -L -x -v -n -t nat --line-numbers
;;
*)
echo "Usage: /etc/init.dfirewall {start|stop}"
exit 1
;;
esac

exit 0
---------------------------------------------------------------------------------------------
 

About

The Proxmox community has been around for many years and offers help and support for Proxmox VE and Proxmox Mail Gateway. We think our community is one of the best thanks to people like you!

Get your subscription!

The Proxmox team works very hard to make sure you are running the best software and getting stable updates and security enhancements, as well as quick enterprise support. Tens of thousands of happy customers have a Proxmox subscription. Get your own in 60 seconds.

Buy now!