| --- |
| title: Disable TCP SYN Cookies |
| --- |
| |
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| |
| Most default Linux installations use SYN cookies to protect the |
| system against malicious attacks (such as DDOS) that flood TCP SYN packets. |
| |
| This feature is not compatible with stable and busy <%=vars.product_name%> clusters. SYN Cookies protection gets |
| incorrectly activated by normal <%=vars.product_name%> traffic, severely limiting bandwidth and new connection |
| rates, and destroying SLAs. Security implementations should instead seek to prevent DDOS types of |
| attacks by placing <%=vars.product_name%> server clusters behind advanced firewall protection. |
| |
| To disable SYN cookies permanently: |
| |
| 1. Edit the `/etc/sysctl.conf` file to include the following line: |
| |
| ``` pre |
| net.ipv4.tcp_syncookies = 0 |
| ``` |
| Setting this value to zero disables SYN cookies. |
| 2. Reload `sysctl.conf`: |
| |
| ``` pre |
| sysctl -p |
| ``` |