em0 hijacking traffic to port 623

[Ian FREISLICH]

John Baldwin wrote:
> On Monday 21 May 2007 07:17:07 pm Jack Vogel wrote:
> > On 5/21/07, Sten Spans <sten at blinkenlights.nl> wrote:
> > > On Mon, 21 May 2007, Ian FREISLICH wrote:
> > >
> > > > Hi
> > > >
> > > > We've noticed an issue on our firewalls where the first em device
> > > > in the system hijacks inbound port 623 tcp and udp.  The OS never
> > > > sees this traffic.  Interestingly, em1 and em2 do not appear to be
> > > > afflicted by this problem.  Some reading I've done points to a
> > > > similar conclusion:
> > > >
> > > > http://blogs.sun.com/shepler/entry/port_623_or_the_mount
> > > >
> > > > I've looked at the bios, but I can't find any settings that remotely
> > > > hint IPMI or RMCP+ or serial-over-lan.
> > > >
> > > > Does anyone know how I can stop the card or system from stealing
> > > > port 623 in hardware or must I just stop using em0 (and/or Intel NICS)?
> > >
> > > Does "ifconfig em0 promisc" help ?
> > > That fixed firmware related vanishing ipv6 packets on fxp and em.
> > 
> > Is this happening even with the latest CURRENT driver,  there is code in
> > it now that is supposed to stop the firmware from doing that, at least
> > that was the theory :)
> 
> We still see this at work.  We use this workaround in /etc/sysctl.conf:
> 
> net.inet.ip.portrange.lowlast=665
> 
> It seems that the em0 interface always snoops 623 looking for RCMP
> packets for IPMI (or ASF).

===================================================================
RCS file: /home/ncvs/src/sys/dev/em/e1000_82540.c,v
retrieving revision 1.3
diff -u -d -r1.3 e1000_82540.c
--- e1000_82540.c       16 May 2007 00:14:23 -0000      1.3
+++ e1000_82540.c       25 May 2007 13:40:19 -0000
@@ -316,6 +316,7 @@
        /* Disable HW ARPs on ASF enabled adapters */
        manc = E1000_READ_REG(hw, E1000_MANC);
        manc &= ~E1000_MANC_ARP_EN;
+       manc &= ~(E1000_MANC_RMCP_EN | E1000_MANC_0298_EN);
        E1000_WRITE_REG(hw, E1000_MANC, manc);
 
        E1000_WRITE_REG(hw, E1000_IMC, 0xffffffff);

Fixes it for me.  But, of course, I'm not interested in ASF on my
gateway hosts.

I didn't look further into the initalization of the chip.  The
datasheet I downloaded suggests that you can filter these packets
on IP address as well and I suspect the option is turned on with
some default in the EEPROM register that equates to 0.0.0.0/0.

Ian

--
Ian Freislich