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In the message log of an ECS instance in the Linux system, the "managed promise mode" and "left promise mode" information are displayed

Last Updated: May 20, 2022

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Problem description

The following information is displayed in the message log of the ECS instance in the Linux system.

entered promiscuous mode
left promiscuous mode



According to the log information, the error is not an exception log and has no impact on the server system.

  • "Device eth0 managed probation mode" means that eth0 Nic has entered the mixed mode.
  • "Device eth0 left isolation mode" means that the eth0 Nic exits the mixed mode.


The hybrid mode is a working mode of network interfaces. It is generally used when capturing network interface packets. If this log is displayed in the system log, packets are captured on the NIC on the server. This log is generated by the tcpdump packet capture command. You can use the following command to set the network interfaces to be mixed.

  1. Run the following command to set the eth0 Nic to the mixed mode.
    Ifconfig eth0 promise
  2. Run the following command to disable the hybrid mode of eth0 Nic.
    ifconfig eth0 -promisc


Application scope

  • ECS