Promiscuous mode check

Issues related to configuring your network
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Mike66
Posts: 2
Joined: 2019/07/15 11:34:24

Promiscuous mode check

Post by Mike66 » 2019/07/15 19:34:14

Hello, all.

We have a small problem with promiscuous mode check. There is number of virtual machines running on KVM host. One moment instances couldn't get IP addresses from remote DHCP-server. The reason, I think, is promisc mode turned off on the physical host interface.

The output below is from the problem host. Non-zero promiscuity and flags (0x100) show that promisc is on.

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[root@comp-1 ~]# ip -d link show dev eno2
5: eno2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master team1 state UP mode DEFAULT qlen 1000
    link/ether d8:c4:97:09:86:b4 brd ff:ff:ff:ff:ff:ff promiscuity 2 
    team_slave addrgenmode eui64 
[root@comp-1 ~]# cat /sys/class/net/eno2/flags 
0x1103


But the output above doesn't have PROMISC keyword as in output from the other host with no such problems:

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[root@comp2 ~]# ip -d link show dev eno2
3: eno2: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc mq master team1 state UP mode DEFAULT qlen 1000
    link/ether d8:c4:97:09:8b:3d brd ff:ff:ff:ff:ff:ff promiscuity 1 
    team_slave addrgenmode eui64 
	
[root@comp2 ~]# cat /sys/class/net/eno2/flags
0x1103
Are there any other ways to check promisc mode status?

Thanks.

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TrevorH
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Location: Brighton, UK

Re: Promiscuous mode check

Post by TrevorH » 2019/07/16 12:10:43

You're attaching your guests somehow directly to a physical interface? Do you have a bridge?
The future appears to be RHEL or Debian. I think I'm going Debian.
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 and 6 are deadest, do not use them.
Use the FAQ Luke

Mike66
Posts: 2
Joined: 2019/07/15 11:34:24

Re: Promiscuous mode check

Post by Mike66 » 2019/07/16 13:28:58

Ah, yes, that was openvswitch misconfiguration issue.
By the way, it seems that "PROMISC" absence did not matter - promiscuous mode was on according to flags.
Sorry to bother you.

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