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Jonathan_Briggs's profile

New Contributor

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12 Messages

Fri, Jun 11, 2021 4:31 PM

New Firmware for DPC3941B? New bugs?

I believe that my Comcast provided router, a Cisco DPC3941B, rebooted last night with a firmware update. Although I cannot tell from any of the log files and nothing seems to have a date. But the software version on it now is

DOCSIS Software Version: 2.3.10.13_5.5.0.5
Software Image Name: DPC3941B_3.9p36s1_PROD_sey
Advanced Services: DPC3941B

That reboot, or update, was pretty annoying since it seemed to change the MAC address and the IPv6 link-local on the gateway, which broke IPv6 on one of my static servers.

The new annoyance this morning is that IPv4 access from the internal 10.0.10.0/24 network to the static IP at 74.92.214.37 is not working for Windows machines. It does work for a Linux machine, apparently because it receives a nonsense ICMP Redirect and ignores it.

Check this out:

PING catbox.zlynx.org (74.92.214.37) 56(84) bytes of data.
From _gateway (10.1.10.1) icmp_seq=1 Redirect Host(New nexthop: mm-74-92-214-37.mogilev.dynamic.pppoe.byfly.by (37.214.92.74))
64 bytes from catbox.zlynx.org (74.92.214.37): icmp_seq=1 ttl=64 time=2.66 ms
From _gateway (10.1.10.1) icmp_seq=2 Redirect Host(New nexthop: mm-74-92-214-37.mogilev.dynamic.pppoe.byfly.by (37.214.92.74))
64 bytes from catbox.zlynx.org (74.92.214.37): icmp_seq=2 ttl=64 time=1.66 ms

That redirect host is super suspicious. Look at its numbers. It is the 74.92.214.37 IP address with the bytes reversed! Who is writing this firmware, anyway?

It wasn't doing this yesterday.

Responses

Official Employee

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6 Messages

1 m ago

Hey @Jonathan_Briggs I can definitely take a look into this for you. Can you please send me a private message by clicking the peer to peer chat button in the upper right hand corner? 

New Contributor

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12 Messages

1 m ago

Alright, I was wrong about most of the problems, except for the MAC address changing on the router.

After rebooting ALL of the networking equipment things went back to working as they had before.

The reversed IPv4 address turned out to be a bug in the Ubuntu / Debian iputils package. Weird no one saw that before.

In other words, I don't have a problem anymore.

Official Employee

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5 Messages

@Jonathan_Briggs

 

I am glad to hear everything has been sported out! Please feel free to reach out to us here again in the future should you need any further assistance with your services.