Increase the Max Concurrent Port Connections on Your Network

concurrent_verizon.gif So then, you’ve got the “Fastest Package” for the Verizon FiOS ultra high-speed fiber optic. A whooping 50 Mbps download speed and a 20 Mbps upload speed! That means 802.11b WiFi routers won’t even be able to handle those speeds! Nevertheless, that possible 11 Mbps bottleneck should not be your only concern. If you’re going to be utilizing a number of network intensive applications (*coughGnuettllaEmuleBittorrent*) you’ll need to make some other adjustments to your hardware and software network setup. This is one of many things you can do to optimize the network. However, it is the first thing I try to remember when setting up any node or router on my home network.

Possible Names

This setting has many names. You can look for “Maximum Ports,” “Maximum Number of Connections,” “Max Active Links,” “Max Half-open/Duplex Concurrent Connections,” etc. Like the names imply, this setting controls how many connections can be established between nodes. Why is this important? It allows the client computer to contact many more server hosts at the same time. Off the top of my head, this would be beneficial to multi-segment download managers programs like DownThemAll!, Internet browsers (especially with multiple tabs), and (lower voice) P2P file sharing programs.


A Little History

In many older systems and software setups, this setting was pretty much infinity (more like in the 1000+ ballpark). However, the public saw how viruses/worms spread much faster with these concurrent connections since they can reach many more IP addresses in a shorter amount of time. We also saw how DoS attacks were much easier to execute when infected clients established more simultaneous connections to the same host.

In essence, computer security experts urged developers to drastically lower the max number of concurrent connections since most people won’t be really needing several thousand with normal usage. In fact, after these “security enhancements” not many people noticed anything changed even when Windows Vista Home notoriously lowered the count to only 2 max connections! While I agree with their logic, it is a pain for power users to find and reverse these settings when tweaking network setup. There’s nothing like downloading a Bittorrent file at a speed of 150 kb/sec and discovering that you could have been going at upwards of 400 kb/sec with such a simple tweak!

Bottleneck Culprits

“Enough already! Where’s the tweak?” you ask. Listed in order of modification difficulty, the main “max number of connections” bottleneck culprits are usually the application program, the operating system, the router, the modem, or the ISP.


If you’re using a network intensive application like an Internet browser or a P2P client, chances are that there is a setting to change the number of concurrent connections. In Firefox, it is really easy. Load your browser, enter “about:config” in the URL, and enter “connections” in the “Filter” field. The preferences are pretty self-explanatory. Personally, I like to set each of the settings to at least 100. But that’s just me. If you’re using Internet Explorer, you should know better not to be using such a non-customizable browser that I’m not even going to dignify that with a solution! 🙂


concurrent-emule.jpgDefinitely all P2P clients will have a similar setting. In uTorrent go to “Preferences,” “Bittorrent,” then tweak from there. For eMule, go to “Preferences,” “Connection,” “Connection Limits,” and change “Max Connections.”

Operating System

Microsoft Windows has an uncanny way of not allowing many power user customizations in the operating system. The max concurrent connection setting is no exception in Windows XP. Visit the David Kaspar’s article for more information on changing the limit. Or, if you don’t want to read another article, download this executable patch from LvlLord. Note that some anti-malware and antivirus programs may detect this patch as a threat, so disable your shields first before running. Trust me, I use this patch often!

For Windows Vista, visit TorrentFreak’s article.


Linux users, you’re on your own; I have no idea. I know that most Linux-types are usually adept at deep customizing their systems. So, Google is your friend!


Sadly, many consumer routers do not have this option. So, some of you are on your own. I suggest that you buy a DD-WRT compatible router and flash it with the DD-WRT firmware. You’ll literally be turning your puny $60 router into a $600 worth network router. In DD-WRT, I think they changed the location of this setting. Mine is under the “Administration” tab, under “Management,” under “IP Filter Settings,” and under “Maximum Ports.” Like I said, those without DD-WRT may not have this option. Contact your manufacturer or look for something to the effect of “max ports” or “max connections.”


Modem and ISP

These two potential bottlenecks are almost impossible to configure. If you’re lucky, you are using a configurable modem. Most of the time, ISPs only let us use an issued modem which bar access to settings. Even worse, the ISP may limit the number of connections on their end. For that, there is nothing you can do but call them with a good excuse to change it, which is highly unlikely. “Hello Verizon? I want to share my DVDs on my computer!”

Try these suggestions and post your results or questions here!

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3 Responses to “Increase the Max Concurrent Port Connections on Your Network”

  1. fuq fios Says:

    I’d “upgrade” to fios from 15 mbps TimeWarner if:

    + they would allow mutiple “TAs” on one account
    + didn’t restrict me to using only their smtp server
    + tv service didn’t STEAL bandwidth from my internet connection
    + didn’t make it an uphill battle to have a “dry loop” install
    + billed monthly: to encourage better customer service
    + didn’t cost more for the same f’ing thing
    + didn’t use evil, smallER netblock, geoip registration like TWC

  2. allan Says:

    cool article!

  3. Adam Says:

    #fail article. Most consumer grade routers support somewhere around 200 concurrent connections. Asking the applications to use more than that will make it all slower.

    The Windows setting is not for number of concurrent connections but number of half open connections, which is not the same thing.

    Lastly, Firefox concurrency is set to the amount in the configuration because some web servers don’t allow a higher number of concurrent connections.

    Even though the article is old, it was as wrong then as it is wrong now.

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