Promiscuous Mode ?

[rphanikrishna]

Hi All,

I have some log messages which says "kernel: em0: promiscuous mode disabled" and enabled again, Am only running Unbound DNS resolver in my Freebsd 12.1 release p5. If it is not recomended to change the status can you explain me how to fix the state of promiscuous mode.

 

[pos]

Maybe the process trying to set em0 in promiscuous mode is not root. You have to be root.

 

[rphanikrishna]

I have services running other than root are " unbound , ntpd , smmsp ". Can you let me know if any of these services require that mode to be enabled and if yes then why.

 

[pos]

Not that much info from you
As far as I know, none of your mentioned processes needs promiscuous mode to listen to *all* traffic.

Any bridges? Maybe trying to bind anything to a bridge interface?
Have you mixed with any sysctl settings, or maybe "promisc" flag to ifconfig?
Maybe a network card that does not support promisc? (but you would probably have seen another message if that was a problem)
Or a faulty configured service?

 

[rphanikrishna]

i hosted it on Proxmox KVM, There is no bridge configured in the Freebsd system.

 

[ralphbsz]

Usually, promiscuous mode is used by programs such as tcpdump and friends, to see all traffic on an interface.

 

[rphanikrishna]

Hi how and where do i check which service is using the promiscuous mode.

 

[SirDice]

It's probably not a service (timestamps are too random), more likely is like ralphbsz said, you used tcpdump(1) a couple of times.