[CentOS] Network Diagnostics

Tue Jan 7 13:34:43 UTC 2020
Stephen John Smoogen <smooge at gmail.com>

On Tue, 7 Jan 2020 at 08:22, Chris Olson via CentOS <centos at centos.org> wrote:
> In our smallest office, we have a Dell CentOS 7 system, a
> Windows system and an HP 8610 printer, all hard-wire Ethernet
> connected with a Linksys router. The router provides Internet
> connection. All of the network-connected systems get their
> IP address from the router at power up.
> Successful network connection of the printer at power up
> has recently started taking much longer than usual.  The
> display on the front of the printer indicates that it is
> initially attempting wireless connection even though this
> feature is turned off.  Ethernet connection is eventually
> achieved and the printer functions normally on the network
> but just for a few minutes.
> After about five minutes, the printer drops its Ethernet
> connection and appears to be attempting wireless connection
> once again.  During this period, network connectivity is
> disrupted for the other systems on the network. They are
> not able to communicate with each other or access the
> Internet through the router.  Turning off the printer
> restores network connection for the other systems.
> One of our personnel at another office suggested using
> Wireshark to check out the network when the printer is
> having difficulty.  Wireshark was apparently not on this
> system so we installed it using yum install.  The tail
> end of the apparently successful installation process
> is shown below.  Unfortunately, we cannot seem to find
> Wireshark on the system.
> Is it possible that Wireshark was not actually installed
> or do we just not know how to locate and use it?
> Is this printer networking issue a known problem and is
> Wireshark the right tool to diagnose the problem?
> Thanks.
> Installed:
>   wireshark.x86_64 0:1.10.14-16.el7

The wireshark package by itself only comes with the text tools: tshark
and similar. The wireshark-gnome comes with the wireshark video item

[smooge at xanadu Packages]$ rpm -qlp wireshark-1.10.14-16.el7.x86_64.rpm
 | grep bin
[smooge at xanadu Packages]$ rpm -qlp
wireshark-gnome-1.10.14-16.el7.x86_64.rpm  | grep bin

I will say from the problems in the start of this email that I am not
sure wireshark is going to help show what is wrong. I am expecting
that the printer's network card is broken in some way and is spewing
hardware errors to the network. The linksys switch is a 'dumb' switch
and will go into a hardware reset mode to try and clear it up. I would
try the following:

1. Hardware reset the printer to factory settings and see if it comes
back sane after reset up. If it does not then the problem is a
hardware issue with the printer and either buy a new one or get it
2. If the hardware reset works, then I would run whatever Windows
software configures and updates the printer BIOS and drivers to the
newest from HP. Printers are now a vector for cyber-crime infection
and the problems you are describing are also what one sees in a system
which was sort of taken over.

> Dependency Installed:
>   libsmi.x86_64 0:0.4.8-13.el7
> Complete!
> [user at computer ~]$
> [user at computer ~]$ which wireshark
> /usr/bin/which: no wireshark in (/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:/home/user/.local/bin:/home/user/bin)
> [user at computer ~]$
> Recent successful installations:
> --------------------------------
> [user at computer ~]$
> [user at computer ~]$ which mplayer
> /usr/bin/mplayer
> [user at computer ~]$ which ffmpeg
> /usr/bin/ffmpeg
> [user at computer ~]$
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Stephen J Smoogen.