syncookied emulates linux kernel syncookie functionality by intercepting SYN packets
and sending replies to them using the same cookie generation alghorithm. It can achieve
better performance under SYN flood attacks thanks to kernel bypass (netmap).
- Install rust (instructions here: https://www.rust-lang.org/en-US/downloads.html)
libpcap-devor equivalent package for your distribution
- Install netmap. Make sure netmap.h / netmap_user.h can be found in /usr/include. Alternative you can point CFLAGS variable to their location: example.
cargo build --release, resulting binary will be found in target/release/syncookied.
Note: we use AVX-accelerated SHA1 function by default. SSE3 implementation is also available under sse3 feature flag, i.e.:
cargo build --features=sse3 --no-default-features --release.
How to run
On server you want to protect
- Install tcpsecrets linux kernel mode to expose tcp syncookie key and timestamp
- Start syncookied in
syncookied server <proto://ip:port>. Running this commands automatically starts a TCP or UDP server on specified ip/port and sets
net.ipv4.tcp_syncookiesto 2 on first request.
On server you want to use for packet processing
Install netmap and make sure it works (pkt-gen)
Disable NIC offloading features on the interface you want to use (eth2 here):
ethtool -K eth2 gro off gso off tso off lro off rx off tx off ethtool -A eth2 rx off tx off ethtool -G eth2 rx 2048 tx 2048
Set up queues and affinities. Here we bind 12 queues to first 12 cpu cores:
QUEUES=12 ethtool -L eth2 combined $QUEUES ./set_irq_affinity -x 0-11 eth2
set_irq_affinity is available at https://github.com/majek/ixgbe/blob/master/scripts/set_irq_affinity
Create hosts.yml file in the working directory, which looks like this
- ip: 220.127.116.11 secrets_addr: udp://192.168.3.231:1488 mac: 0c:c4:7a:6a:fa:bf
Here ip is external ip you want to protect, secrets_addr is the address of syncookied server running on protected host, and mac is its MAC address.
syncookied -i eth2. It will print something like this:
Configuration: 18.104.22.168 -> c:c4:7a:6a:fa:bf interfaces: [Rx: eth2/3c:fd:fe:9f:a8:82, Tx: eth2/3c:fd:fe:9f:a8:82] Cores: 24 12 Rx rings @ eth2, 12 Tx rings @ eth2 Queue: 1048576 Starting RX thread for ring 0 at eth2 Starting TX thread for ring 0 at eth2 Uptime reader for 22.214.171.124 starting ...
Configure your network equipment to direct traffic for protected ip to syncookied.
You can reload configuration at any time by changing hosts.yml and sending HUP signal to syncookied. It will print something like this:
Uptime reader for 126.96.36.199 exiting All uptime readers dead Old readers are dead, all hail to new readers Uptime reader for 188.8.131.52 starting ...
Enjoy your ddos protection
syncookied has some options you may want to tune, see
If you have more than 1 interface on your server, you may want to look into -O to use second one for TX.
This greatly improves performance and latency as forwarding and syn-reply traffic is separated.
It's possible to filter traffic by adding "filters" section to host configuration like this:
- ip: 184.108.40.206 secrets_addr: 127.0.0.1:1488 mac: 0c:c4:7a:6b:0a:78 filters: tcp and dst port 53: drop tcp and dst port 22: pass default: pass
Filters are written in pcap syntax. Consult
pcap-filter(7) for more information.
Default policy is "pass". It can be changed by using
Note that filtering happens on layer 4.
Please check the FAQ before filing an issue.
Join us on Telegram: https://telegram.me/syncookied
syncookied is distributed under the term of GPLv2.