DHCP server for freebsd on IPoIB

Rodney W. Grimes freebsd-rwg at gndrsh.dnsmgr.net
Thu Feb 13 03:25:08 UTC 2020

> On 2020-02-12 20:53, Rodney W. Grimes wrote:
> >> On 2020-02-12 18:19, Rodney W. Grimes wrote:
> >>> Is there support in FreeBSD for bpf at the IB link layer?
> >>>
> >>
> >> BPF support is added per driver. And from my quick grep, ipoib supports
> >> BPF. But the format may have a fake ethernet header.
> > 
> > So that is close, but not exactly what I was asking.  Specifically
> > I did not mention ipoib, I want to know can I bpf dump packets at
> > the link layer regardless what the layer 3 protocol is.
> > 
> > And from reading the other email it sounds as if this "fake ethernet
> > header" is what is getting in the way of bpf into ipoib working.
> You mean the infiniband packets, which wrap the IP-packets?

I mean when dhcpd tries to send a packet it ends up someplace
in the ipoib as an output packet and that output packet processing
decides it has an ethernet frame type so drops it since we
do not support EthoIB.  This fake ethernet frame type evidently
comes from the way bpf is hooked into ipoib.

I think the original poster has already tracked it down to that
and is asking for help in how to fix the code so that it works.

> --HPS
Rod Grimes                                                 rgrimes at freebsd.org

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