Friday, August 11, 2017

conserve mode FortiGates

Within in the Fortigate models, you have a conserve mode. This is a simple method that FortiOS triggers in order to try to  protect  the systems.

Almost all security profiles are handle in shared memory. Any time this memory is exhausted or nearly exhausted the  unit will go into  conserver mode and deactivate certain scan profiles.

You can easy check if your  unit is in conserve mode by the following diagnostic command;

diagnostic hardware sysinfo shm | grep conser

You can also review logs , if this event happens it will be recorded as a "critical" event .


Okay to  avoid this, we need to understand the following;

  • Combinations of AV-profile  scanning with  proxy/flow mode can cause havoc conserve-mode
  •  excess traffic and utm-function can cause  kernel conserve mode
  • it best to be aware of running  multiple  scan mode flow or proxy
  • Limit what fwpolicies have  AV-profiles
  • Upgrade the unit if it's under-size  and if repetitive  conserve-mode events happens

So to ensure you don't enter conserver mode you need to reduce logging-to-memory.

Various fortigate-models  uses a certain  % of the shared-memory or physical-memory thresholds  to determine when it goes into  conserve-mode . The FTNT support-team  can provide you these values upon request.

It's best to optimized the firewall just for the UTM features that you  required and disable all other utm and profiles from the firewall-policies.

Ken Felix
NSE ( network security expert) and Route/Switching Engineer
kfelix  -----a----t---- socpuppets ---dot---com
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