Just wanted to follow-up and confirm everything is working OK now. Here is a summary of my setup that is performing extremely well. I basically salvaged an old gaming system from 2007 that I still had laying around plus a few new parts. While it seems like overkill, I can run ShowEQ with the fast machine option and session tracking options and pump up the FPS to make it seem more real-time since everything is running internally at gigabit LAN speeds.

Asus Striker Extreme LGA 775 core 2 duo 6700 @ 2.66 GHz nVidia nForce 680i
nVidia GeForce GT 220
6 GB DDR2 memory
500 GB SATA drive
1920x1080 24" monitor (extra screen real estate really is nice)

The two embedded 10/100/1000 nForce NICs using forceDeth driver are disabled (eth0 and eth1)
2 PCI gigabit NICs installed (D-Link and TrendNet)
- eth2 is enabled for normal internet usage and connected directly to my normal network router/switch
- eth3 (promisc) is connected to a dedicated switch (see below)

The key to making everything work is the Netgear ProSafe GS108E V3 8-port switch with port mirroring. These are currently available online and in most computer stores. I tried other switches that claimed to have port mirroring but something about this particular switch allows it to be "hub-like" instead of restricting the destination port from monitoring activities only. In other words, when I plug my CentOS eth3 connection into the mirrored destination port, it still is able to get an IP via DHCP and act somewhat normal. Other switches I tried did not allow for this functionality at all and were restricted by design to only monitor. Apparently from my testing experience with other consumer level switches, even though Wireshark and tcpdump can see both RX and TX packets from the EQ client IP or MAC, ShowEQ will not play nice unless it has this old school hub type functionality.

Installation / Configuration:
- CentOS 6.8 32-bit 2.6.32-642.11.1.el6.i686 (default desktop installation)
- Running Gnome 2.28.2

Here is the only software that was added after the initial CentOS installation:
- First, used software update in System - Administration panel to update the general system
- Next, installed the following packages via yum:
subversion
gcc
automake
gcc-c++
zlib-devel
gd
gd-devel
libtool
qt-devel
qt3-devel
qt3-devel-docs
libpcap-devel
wireshark
wireshark-devel
wireshark-gnome

Uninstalled the terrible NetworkManager service and applet entirely following these instructions:
https://access.redhat.com/documentat...k_Manager.html

Configured all the network interfaces manually by editing the files in /etc/sysconfig/network-scripts/
Executed showeq with the following command as root: /usr/local/bin/showeq -i eth3

I have tested both the SVN code and the installation tarball for version 5.13.10.45 and can confirm both are working. I also added showeq-maps-master and filters-5xx-06-20-05 following the instructions available in other posts. It seems there are many ways to run ShowEQ these days and this is just one option out of several. It worked for me and the only hardware I had to purchase was the GS108E switch which runs about $50 USD at most places.