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Conntrack table memory usage

Discussion in 'Asuswrt-Merlin' started by Denna, Apr 20, 2017 at 8:41 PM.

  1. Denna

    Denna Regular Contributor

    Aug 4, 2016

    I've been looking at ways to minimize router resource usage caused by external Internet hosts.

    One of the ways to minimize CPU usage and conntrack table entries was to implement the following rule.

    iptables -t mangle -I PREROUTING -i <wan_face> -m state --state NEW -j DROP
    On an Asus RT-AC88U, if you run the following command ...

    sysctl net.ipv4.netfilter.ip_conntrack_max
    ... you get 300,000.

    Does that mean this router is configured with a maximum of 300,000 simultaneous connections ?

    If each conntrack entry is 350 bytes, doesn't that amount to more than 100 MB of memory usage ?

    Is that right ?​
    Last edited: Apr 20, 2017 at 8:46 PM

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