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Sunday, March 1, 2015

DDoS (Distributed Denial of Service) Protection - RHEL 7




Netfilter: iptables target SYNPROXY
DDoS attacks are increasingly becoming commonplace as more and more products and services become dependent
on delivering services over the Internet.
SYNPROXY module is designed to protect against common SYN-­floods and ACK-­floods, but can also be adjusted to
protect against SYN-­ACK floods.
Works by filtering out false SYN-­ACK and ACK packets before the socket enters the “listen” state lock (otherwise
preventing new incoming connections)
Significant step for fighting DDoS and protecting critical system services.
Example configuration (intended for a web server):
sysctl: net.netfilter.nf_conntrack_tcp_loose=0 [DEFAULT=1]
# iptables -­t raw -­A PREROUTING -­i eth0 -­p tcp -­-­dport 80 -­-­syn -­j NOTRACK
# iptables -­A INPUT -­i eth0 -­p tcp -­-­dport 80 -­m state UNTRACKED,INVALID \
-­j SYNPROXY -­-­sack-­perm -­-­timestamp -­-­mss 1480 -­-­wscale 7 –ecn
DDoS

1 comment:

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