Snort in 2.4 - High CPU utilization

  • Snort is utilizing increasingly high CPU% since upgrading to 2.4

    Current utilization w/ <2 mbps traffic and 2 days of uptime:
    The WAN Snort interface is utilizing 50-80% CPU
    LAN is utilizing 40-50%
    VPN snort interface is using very low amount(low traffic)

    After restarting the Snort service the CPU utilization becomes:
    WAN: 1-10-%
    LAN: 10-20%
    However, the utilization steadily increases over time.

    Admittedly I never monitored Snort resource utilization before the upgrade so I don't know if this is normal.

    It seems like the CPU utilization would correlate with the amount of traffic traversing the interface, but this is not the case.

    Is anyone else having this issue?

  • No one can tell you if that's normal without knowing bandwidth, CPU, and ruleset.

    You've got 1 of 3, let us know the other 2 pieces and we can help more.

    It also depends on what kind of traffic traverses the network.

    If you're running 2mbps of traffic through a long list of complex rules then you could significantly tax even a powerful CPU.

    Conversely, if you're using an old atom even a very light ruleset would bring it to its knees.

Log in to reply