[ale] Strange Linux networking issue

Jim Kinney jim.kinney at gmail.com
Mon Apr 19 14:17:26 EDT 2021

Two hosts directly connected with neither switch nor cross-over cable.

Sounds like the two nics auto-negotiated themselves to death.

To test, stop networking on boxA, rmmod nic modules, insmod nic modules, start networking. If ping runs a bit after that, disable autoconfig.

On April 19, 2021 1:06:07 PM EDT, Derek Atkins via Ale <ale at ale.org> wrote:
>I'm having a strange networking issue between two AWOW devices running
>Linux that stopped talking to each other.  The devices are configured
>--(a)[Box 1](b) ----- (c)[Box 2](d)--
>(a) is
>(b) is
>(c) is
>(d) is
>The (b)/(c) link is a direct link between the devices, not a crossover
>cable, and no switch.
>The two devices were talking fine for a while and then all of a sudden
>they stopped.  Now that won't talk at all.  When truing to ping .7.100
>from Box 1, it sends out ARPs but there is no ARP response from Box 2. 
>Similarly, on Box 2 trying to ping .5.1 results in no ARP responses.
>Both devices show the (b)/(c) link as up.  Running ethtool shows the
>is detected.  However arp -an shows an incomplete response (no
>The dmesg output doesn't show anything.
>I am at a loss. I don't understand how or why the two devices would
>talking, and why neither will pick it up again.
>Any suggestions for where to look or how else to debug this?
>       Derek Atkins                 617-623-3745
>       derek at ihtfp.com             www.ihtfp.com
>       Computer and Internet Security Consultant
>Ale mailing list
>Ale at ale.org
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