Author Topic: HOWTO: Filesharing via Wifi  (Read 32078 times)

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Offline scripter

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HOWTO: Filesharing via Wifi
« on: July 25, 2008, 02:11:17 AM »
With ISPs throttling and agreeing with big corporations to punish people who use the bandwidth they are paid for, you may want to know more about filesharing over Wifi.

The good news? P2P over Wifi is faster, a lot faster.

Wifi upload speeds are *not* lower than download speeds.

Wifi avoids corporate ownership and other BS. You can do it yourself.

Universities and other organizations don't own the Wifi airwaves and can't regulate them.

You can connect to others up to 16 miles away with an external antenna!

How can I share files over Wifi? Is that a Frequently Asked Question? Let me answer:

In this HOWTO, you need a friend or friends nearby, 2 wireless routers or interfaces, patience, a little persistence, and a P2P program that allows *wired* LAN sharing.

A off the shelf Wifi router or USB device can create a simple network called "adhoc". This kind of network is simply an extension of your home wired network.

You will need to know a few things, like how to get to the settings screen of your router or device.

Most routers, such as the Linksys WRT54G, use your browser to get to the settings screen. You should read the manual that came with it, but most are reached at http://192.168.0.1/ or http://192.168.1.1/ or possibly http://192.168.2.1/ you then enter a default username and password (see the manual).

If you are going the router method, see below for more information on software mods you may need.

A USB device like the Linksys WUSB11 or Netgear has it's own setting screen (see the manual).

At this point you are looking for wireless settings such as SSID and connection type, things like "infrastructure" or "adhoc".

You want "adhoc", and you need to pick a name for the "SSID", it's the wireless network's name, both you and your friend's router/device should have the same name, like "freedom" :)

If you are using a USB device, you need to set a static IP different than the other guy's IP. Keep reading and you will get the idea.

There are several ways to do the next part, but the easiest way with a router is to tell one to start giving out IP's different than the other router.

Look for a setting for "DHCP" or "Network Address Server Settings", look for a setting like "Starting IP Address" which might be set to 192.168.1.100, or 192.168.1.3, something like that.

This is the number where the router gives the connected computer it's IP address when you first turn the computer on. What you want is the other router to start giving out IPs different than the other.

Change one router to something like 192.168.1.110 so now it starts at 110 with the first computer that is connected.

So now one computer will be at 192.168.1.100 and the other at 192.168.1.110 good enough.

Now run your P2P program and give it those two IPs and see what happens.

Simple, fun little network. Tell your ISP to eat dirt!

Want more details? Keep reading and I'll ramble on....

In some cases your local firewall may have to be changed to allow incoming connections from the local network, or on the port that your P2P program uses. Look for posts or documentation on your P2P program about opening firewall ports etc..

If you are still having problems, check the IP address of the computers, check the P2P program settings or try other P2P programs. Not all of them let you connect to 192.168.X.X (local LAN) addresses.

Another thing you may run into is the need for "port forwarding". You can look that up via google if you need the info but in most cases "adhoc" networks aren't using the "NAT translation" routing system and don't need port forwarding.

There are a lot of other things you can try but this kind of network is simple, quick, and uses cheap off the shelf equipment. You can add a number of friends to the network, as long as they can all "see" each other over the wireless. You may be able to add a "range extender" to the network to get more distance or "see" around corners. Be creative.

If you want to use routers you need to find one that supports dd-wrt, see the links below for a list of supported routers. This type of software lets you go "adhoc" with other devices, like a USB device also increase power. Routers let you connect external antennas easily.

USB devices are great because you can put them on USB extender cables and place them in a window, high up or outside. You may be able to go up more than 50 feet!

Don't forget that 2.4 Ghz signals can bounce off of buildings and other objects to get you around obstructions, you may just need a directional antenna to boost the signal.

Bandwidth on Wifi 802.11b is 11M bit/s max. That would be with a strong signal. As you lose signal strength over distance the speed automatically goes down in steps to a 1M bit/s rate.

Start small. It's easier if two friends start this and show two more friends and let them show two more. At some point when things get out of hand you may have to change your network into a "mesh" network or add "bridges" to make the network into sections. If you get to that point, please post and I'm sure there's help out there.

Don't forget there's directional antennas that boost signal, even small ones that don't cost much. Sometimes just moving an antenna to a new position makes the signal stronger. You can avoid interfering signals the same way. Some houses have wire mesh inside the walls, so placing the device in a window can help.

Your friends should all agree to use one P2P program on the network and not use wireless to connect to the internet. One of the friends could agree to run two copies of the P2P program at the same time, one on the *wired* internet to give access to outside content as a sort of "gateway" to the outside world.

On this simple network, anyone trying to use internet over the wireless will not be happy since P2P will flood the thing most of the time. So no wifi internet, sorry, don't ask, get your own. It's up to your group of course, I'm just making suggestions. It's going to take some work to make this ***simple*** adhoc network internet access compatible anyway.

Safety and privacy are concerns for everyone so pick a safe P2P program that gives you safety even on the internet. Why chance it? Planet Peer wiki/forums has a lot of info on your choices.

If you want to test this before you buy wifi routers you can try the same thing with a wired ethernet network, just set static IPs for each computer and set firewalls as needed.

It's possible to use two ethernet cards on one computer so you can have one wired connection to the internet and the other to the wifi router. You may be able to create a "virtual" network interface on the same card and use the same wires but that's another topic for another time.

The reason I picked the Linksys WRT54G is that it has a standard external antenna connections and runs DD-WRT (if you want to increase power output later on), and supports other downloadable programs. Some D-Link models have external connectors too.

Older WRT54G's had more memory and you may be able to find good used ones on the net if you want to run things like DD-WRT. The newer WRT54GL is sold for use with software like DD-WRT. Not all routers support DD-WRT, see below for a list.

Another device is a "Ethernet Bridge", like a Linksys WET200. It's basically a box that extends a wired ethernet network over wireless. Just giving you ideas here.

Please feel free to post your experiences and other useful information I should add to this post or post this to a wiki if you like. (EDIT: Lots of changes since my first post, thanks for the comments)

Answers to other Frequently Asked Questions about Wifi, try these links:
Pics of one type of antenna that can get you 16 miles or more
http://www.radiolabs.com/products/antennas/2.4gig/2.4-aluminum-parabolic.php
ISPs in the UK agree to work with the **AA corporations
http://torrentfreak.com/uk-isps-to-start-sending-mass-080724/
Open source, easy to use replacement software for wifi routers, lets you change output power
http://www.dd-wrt.com/
List of DD-WRT supported devices
http://www.dd-wrt.com/wiki/index.php/Supported_Devices
Creating an ad hoc WiFi network (win XP info)
http://en.kioskea.net/configuration-reseau/creer-reseau-wifi-ad-hoc.php3
WiFi Adhoc Mesh with OLSR (2005 article, look for newer software)
http://www.ccirrus.per.sg/rfc13109/2005/12/wifi-adhoc-mesh-with-olsr/
Freifunk Firmware (for wireless mesh networks and other Wifi info)
http://ff-firmware.sourceforge.net/
Wireless Networking in the Developing World (english, free PDF available)
http://www.lulu.com/content/223168
Mesh - Drahtlose Ad-hoc-Netze (german)
http://www.ixsoft.de/software/products/OS9783937514390BK.html
Google will answer just about anything
http://www.google.com/
« Last Edit: August 27, 2008, 05:45:10 AM by scripter »

Offline Nightwalker_z

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Re: HOWTO: Filesharing via Wifi
« Reply #1 on: July 25, 2008, 06:03:10 AM »
Good idea - but .... :-)
- be careful with big utilized cells. In one radio cell, the clients share the available bandwidth, which could be very low in bad conditions.
- big broadcast/collision domains could occur... BAD THING.

Bandwidth on Wifi 802.11b is 11M bit/s max. That would be with a strong signal. As you lose signal strength over distance the speed goes down in steps to a 1M bit/s rate.
Hmm ... could sound confusing for some people. The 11Mbit/s in 802.11b or the 54Mbit/s in 802.11g or 802.11a, are the DATA RATES.
The throughput is different. This is caused by collisions, retransmissions, 802.11 control (ACK, CTS, CSMA/CA ...).
So, in real life, the throughput is much lower than the data rate.
For example: In an 802.11g network the maximum throughput is approximately 25Mbit/s (when having a data rate of 54Mbit/s). But this is only possible under good conditions (SNR > 25 dB). Over long distances, that data rate lowers to 6Mbit/s (lowest 802.11g value), which results in 1-2 MBit/s throughput. This throughput is shared throughout one radio cell.

It's a myth, that WLAN is fast. Only under good conditions and no interferers, it is "pretty good"
Be aware, that there are just three non-overlapping channels in 802.11b/g (2,4Ghz). So if you using a long distance connection, there is a great change, the signal gets interfered somehow (other WIFI, DECT, baby phones, Bluetooth .....), which results in poor performance as well (noise).

My conclusion:
 + Good idea
 - I doubt, that it is really faster than traditional high-speed Internet connections.
 - Ad-hoc WLAN is not as stable as internet connections (routing, unpredictable, big collision/broadcast domains).

Offline scripter

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Re: HOWTO: Filesharing via Wifi
« Reply #2 on: July 25, 2008, 07:11:13 AM »
It's a myth, that WLAN is fast. Only under good conditions and no interferers, it is "pretty good"
Be aware, that there are just three non-overlapping channels in 802.11b/g (2,4Ghz). So if you using a long distance connection, there is a great change, the signal gets interfered somehow (other WIFI, DECT, baby phones, Bluetooth .....), which results in poor performance as well (noise).
It's not as bad as you think.

The 16 mile connection was getting download speeds averaging about 700K bit/s (802.11b only). The signal was somewhat good because of the directional antennas but was generally on the low end of the scale.

There were times when the signal got bad, maybe due to some other signals, but it would come back. A lot of P2P programs retry packets, and it wouldn't be hard to create a "wifi" mode you can select so it times out TCP connections faster and then reconnects right away since TCP can get stuck sometimes. UDP may prove to be a good choice over wifi.

And if there are other stations out there blasting packets, if they are close to each other then they are sending shorter bursts of signal (faster data rate) and the longer distance "slow" signals may just ride right over them. Or maybe because of the strong signal coming out of the higher db antenna, the other nodes hear it and shut up and wait!

There's a lot of factors to be considered. I tested some routers one time that were close together with two different downloads going on the same channel, not a problem, speeds were good. The code in these radios seem to avoid conflicts pretty well. I was impressed.

You are right though, if you had too many people sharing adhoc things might slow down since everyone "hears" everyone else, but that's a good thing because then you have enough interest to start adding bridges, changing channels on parts of the network, and other things.

Some P2P methods are perfect for this, like if they pass packets through nodes, or store and forward. Then not all the nodes have to "hear" each other.

If you were at 5M bit/s I think you could have 20 nodes easy on the same channel that "hear" each other without losing bandwidth.

So lets say everyone gets 1M bit/s sustained on the little friends network with nodes about 1 mile apart or less. Is that so bad?

And don't forget about the upload vs. download speed of a ISP connection. And the throttling. And the nasty letters.


Offline Nightwalker_z

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Re: HOWTO: Filesharing via Wifi
« Reply #3 on: July 25, 2008, 07:33:43 AM »
If you were at 5M bit/s I think you could have 20 nodes easy on the same channel that "hear" each other without losing bandwidth.
So lets say everyone gets 1M bit/s sustained on the little friends network with nodes about 1 mile apart or less. Is that so bad?
Not correct - the available bandwidth of the channel is shared between the 20 nodes.
So if all nodes want to send at the same time, each node gets 250kBit/s (assuming you have 5Mbit/s throughput not data-rate).
Try it - make an AD-HOC network with 5 clients und start an iPerf server. There are perfect ways to simulate this.
 

Offline Nemo

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Re: HOWTO: Filesharing via Wifi
« Reply #4 on: July 25, 2008, 12:07:30 PM »
In this HOWTO, you need a friend or friends nearby, 2 normal wireless routers, patience, a little persistence, and a P2P program that allows *wired* LAN sharing.

A off the shelf Wifi router can create a simple network called "adhoc". This kind of network is simply an extention of your home wired network.
Excuse me for more critics: Your subject is "HOWTO..." and you posted it in the FAQ part of Planet Peer. The readers now except a solution and a step-by-step description to "Filesharing via Wifi", but it seems you didn't try your ideas in detail...  :(

Most (or all?) off the shelf router aren't able to do Ad-Hoc modus with their original firmware. WLAN access points in the shops are always in Master mode, because this is the usual use case for this device.
You mentioned DD-WRT, this alternative Open Source firmware doesn't work on every Wifi router!!! You should mention in your howto that there's a list of supported devices.
You mentioned the router Linksys WRT54G. It's a fantastic device which runs well with the OpenWRT firmware or Freifunk Firmware (for wireless mesh networks) or many other firmware variants, has an ethernet switch, external antennas, power supply is widerange (ca. 4..24VDC, perfect for homemade power-over-ethernet) and users have many restore options; but these alternative firmwares work only well on Linksys WRT54GL! As mentioned on the wikipedia page Linksys sells it's Linksys WRT54G version 5.0 and higher with reduced hardware (less flashstorage, less RAM), only the WRT54GL is officially sold as GPL-device and is recommended in Freifunk communities.

Quote
There are several ways to do the next part, but the easiest is to tell one of the routers to start giving out IP's different than the other router.

Look for a setting for "DHCP" or "Network Address Server Settings", look for a setting like "Starting IP Address" which might be set to 192.168.1.100, or 192.168.1.3, something like that.

This is the number where the router gives the connected computer it's IP address when you first turn the computer on. What you want is the other router to start giving out IPs different than the other.

Change one router to something like 192.168.1.110 so now it starts at 110 with the first computer that is connected.

So now one computer will be at 192.168.1.100 and the other at 192.168.1.110 good enough.
One important point: Change the default IPs of the Wifi routers too! If you create a wireless bridge and every device (on cable or wireless) is in the same ethernet-broadcastdomain, then it can't work if both routers have the 192.168.1.1 IP address... This setup is simple for LAN-based filesharing (Windows filesharing).
If you want to do some routing then the routers need different IPs on their wifi-interfaces in the same IP-range (e.g. 192.168.1.1 and 192.168.1.2, subnetmask is 255.255.255.0). Then LAN1 is perhaps 192.168.101.0/24 and LAN2 192.168.102.0/24; now you need entries in the routing tables of the Wifi routers (LAN2 via gateway 192.168.1.2 and LAN1 via gateway 192.168.1.1).

This simple scenario will get very complex if you have 5+ wifi routers and the wifi router owners want to use Internet access via their own router at the same time and the IP ranges 192.168.x.0/24 are already in use in their private network... Perhaps you can do some tests with your friend with WDS, wireless bridge in DD-WRT, ad-hoc with/without routing, wireless mesh network for comparing speed and usability?


Just my two cents.

Greetings,
Nemo.

Offline Nemo

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Re: HOWTO: Filesharing via Wifi
« Reply #5 on: July 25, 2008, 12:55:51 PM »
It's a myth, that WLAN is fast. Only under good conditions and no interferers, it is "pretty good"
Be aware, that there are just three non-overlapping channels in 802.11b/g (2,4Ghz). So if you using a long distance connection, there is a great change, the signal gets interfered somehow (other WIFI, DECT, baby phones, Bluetooth .....), which results in poor performance as well (noise).
It's not as bad as you think.

The 16 mile connection was getting download speeds averaging about 700K bit/s (802.11b only). The signal was somewhat good because of the directional antennas but was generally on the low end of the scale.
Using directional antennas on both sides is important for long links: directional antennas boost the sending and receiving signal and they "listen" only in one direction (almost no noise from other directions). To stay legal in Europe you have to reduce the transmit power to 100mW EIRP (=20dBm) for 802.11b/g, 802.11a has other limits.

Two links for theorethical radio link planning:
http://www.swisswireless.org/wlan_calc_en.html
http://huizen.deds.nl/~pa0hoo/helix_wifi/linkbudgetcalc/wlan_budgetcalc.html


Quote
There were times when the signal got bad, maybe due to some other signals, but it would come back. A lot of P2P programs retry packets, and it wouldn't be hard to create a "wifi" mode you can select so it times out TCP connections faster and then reconnects right away since TCP can get stuck sometimes. UDP may prove to be a good choice over wifi.
About TCP settings: I think retransmission times and other parameters are systemwide configurated in the operating system..? Is it possible for an application program to request other parameters for it's TCP connections?


Quote
And if there are other stations out there blasting packets, if they are close to each other then they are sending shorter bursts of signal (faster data rate) and the longer distance "slow" signals may just ride right over them. Or maybe because of the strong signal coming out of the higher db antenna, the other nodes hear it and shut up and wait!
Wifi has a problematic characteristic: Example: node A <-> node B <-> node C.

-If node A transmits a packet and node B can receive it, then it's very possible that node C (is a little away from the others) can't decode the transmission but gets an interference (noise). Increasing transmit power would lead to more noise for other stations, so reducing transmit power is the way to go in a crowded wireless mesh network (speak quietly, listen carefully).

-In case where node A and node C want to talk to node B at the same time we have the hidden node problem (that's a typical situation in a wireless mesh network...).
Using the RTS/CTS-function may work in smaller networks, but not in big mesh networks (mutual blockade is possible) and it slows down the data rate. In Freifunk networks the use of this function is not recommended; the hidden node problem hasn't a solution yet and upper transport layers retransmit the data.


Greetings,
Nemo.

Offline Nightwalker_z

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Re: HOWTO: Filesharing via Wifi
« Reply #6 on: July 26, 2008, 03:39:42 AM »
Using directional antennas on both sides is important for long links: directional antennas boost the sending and receiving signal and they "listen" only in one direction (almost no noise from other directions). To stay legal in Europe you have to reduce the transmit power to 100mW EIRP (=20dBm) for 802.11b/g, 802.11a has other limits.
Using directional antennas with high gain, can be compared with an area.
For example:
If you use standard antennas, you cover an area of 3 x 3 meters = 9mē (JUST AN EXAMPLE VALUE).
If you want to use directional antennas, the resulting area (9mē) must be the same. But you could have an area like 1 x 9 meters or 2 x 4,5 meters...

Here's a list of maximum power to antenna gain (2,4 GHz band):
Antenna Gain Maximum Power Level
2,2dBi50mW
5,2dBi25mW
6dBi25mW
6,5dBi12mW
9dBi12mW
10dBi6mW

For 802.11a, there are some other limits. In Germany it is mandatory to use the extension 802.11h for outdoor applications.
802.11h introduces DFS (Dynamic Frequency Selection) and TPC (Transmit Power Control).
DFS is mandatory; TPC is optional.
DFS is there to avoid interference with one critical application - flight radar. If radar is detected the channel is switched. 802.11h compatible clients has to be informed about the channel shutdown --> They have to change the channel at the same time, to retain connectivity.

But 802.11a is not that popular right now.... nevertheless it's a great option for mesh networks:
The AP communicate via 5Ghz band (802.11a/h) and the clients can communicate via the 2,4Ghz band. This is how Cisco does it at least. The mesh network implementation of Cisco is not that bad - I tested it in a Lab environment. This document is good to see how compicated mesh networks are and what has to be considered:
http://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob41dg/ch8_MESH.html
I doubt, that 802.11 ad-hoc mode is that scalable from the routing, loop prevention etc... point of view.


Offline scripter

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Re: HOWTO: Filesharing via Wifi
« Reply #7 on: July 26, 2008, 06:22:48 AM »
Nemo, thanks and I will try to update my "FAQ", frequently asked questions when you want to know how to P2P over wifi :)

Wifi theory is fun and everything, but there's lots to consider in real world installations.

802.11b uses "direct sequence spread spectrum" (DSSS), just call it frequency hopping. That's probably one of the reasons why when I did my test years ago with two downloads on the same channel and it just worked.

The hidden node problem can happen easily with a node 1/4 mile from one end of a 16 mile link so you would think both nodes are slowed down, but for whatever reasons, in the real world it's not as bad as you think.

There's the "stomp" on the other node situation. Your antennas are picking up the signal of the other node you want at an increased strength, so if you are in the middle of a packet transfer and some other station transmits, you "stomp" on them and just keep on going.

You also have nodes at different distances, directions and even "side lobe" paths from each other.

Oh, and don't forget about the "redundant bit patterns called chips", bits that provide a sort of error correction for noisy envronments.

What about when the speed is automatically reduced and then it's increased automatically?

When rates get faster they use "complementary code keying" (CCK) and the modulation becomes QPSK, while you may be BPSK at the slower speeds over a long distance link.

When you are going slower than other stations the higher rates probably look like small noise blips and are ignored.

Try to calculate all that into the theories and simulations.

As for mesh, I was trying to keep it simple for people who just want to get started. At some point if they find problems from too many nodes, they could divide their little network up with a special node "repeater", change channels every 2 miles, use special P2P nodes as a hub, create a backbone at 5Ghz like Nightwalker said, once it's started then people will get creative.

And as for people trying to get internet over this simple filesharing method, that's not the point. You are trying to get away from the ISP and internet for filesharing.

I say, just try it. Have some fun. See what happens.

And as for power output regulations, do you know anyone who's been taken away lately for putting out a few more mW on wifi?

And remember, with DSSS and directional antennas it's harder to interfere with other stations. It's not like you are transmitting a solid carrier wave constantly.

Oh, and sorry Nemo, all routers should do adhoc because it's part of the 802.11b standard. I know the Linksys, D-link and Netgear ones do.


Offline Nightwalker_z

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Re: HOWTO: Filesharing via Wifi
« Reply #8 on: July 27, 2008, 06:04:26 AM »
802.11b uses "direct sequence spread spectrum" (DSSS), just call it frequency hopping. That's probably one of the reasons why when I did my test years ago with two downloads on the same channel and it just worked.
Sorry - wrong again. Frequency hopping is FHSS and not used for 802.11b.
802.11b uses DSSS (Direct Sequence Spread Spectrum). With DSSS the signal is spreaded to 22MHz width using the barker code. The result is, that the signal is more resistant against damages.
Two adjacent equal channels do work. There are just more collisions and stuff. The resulting bandwidth - and so the rannge in both cells lowers.

Oh, and don't forget about the "redundant bit patterns called chips", bits that provide a sort of error correction for noisy envronments.
? Not in the 802.11 standard. Error recongition is based on the ACK frames and checksums.

When rates get faster they use "complementary code keying" (CCK) and the modulation becomes QPSK, while you may be BPSK at the slower speeds over a long distance link.
At faster data rates, CCK AND QPSK ist used?
I guess you mixed something up. 802.11b always uses DSSS as transmission method (CCK is not a transmission method, it's a modulation method).
1 Mbit/s - BPSK; 2Mbit/s - QPSK; 5,5Mbit/s - CCK; 11MBit/s - CCK.

As for mesh, I was trying to keep it simple for people who just want to get started. At some point if they find problems from too many nodes, they could divide their little network up with a special node "repeater", change channels every 2 miles, use special P2P nodes as a hub, create a backbone at 5Ghz like Nightwalker said, once it's started then people will get creative.
Sounds chaotic to me. If you want to reach a lot of people, standards have to be used.

Oh, and sorry Nemo, all routers should do adhoc because it's part of the 802.11b standard. I know the Linksys, D-link and Netgear ones do.
AD-HOC is part of the complete 802.11 standard (not just b). You are correct, that it is in the IEEE standard. But using an AP implies, that it's and BSS (Basic Service Set) or ESS (Extended Service Set) and so always the infrastructure mode. Only clients have to have an IBSS (Independend Basic Service Set) mode to fulfill the 802.11 requirements.
Conclusion: AP has to support BSS and ESS. Client has to support IBSS.



Offline Nightwalker_z

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Re: HOWTO: Filesharing via Wifi
« Reply #9 on: July 27, 2008, 06:34:26 AM »
Don't get me wrong here. I like the idea - but that's just it - an idea...
What bugs me a litte bit is that there is no concept behind all that. Your HowTo is like "Just take an AP and have fun". I don't think that's the way it works. Especially in big environment you need structure. Have you though about corner-cases, Hidden-Nodes, some weak path because of interference, routing decision, encryption [and a lot of more things]. WLAN is a great thing, but no as easy as you think. Especially it is very easy to attack in terms of data integrity and availability (DoS). Basically I guess it's the worst media to use, because there are so many challanges and weaknesses :-)


Offline scripter

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Re: HOWTO: Filesharing via Wifi
« Reply #10 on: July 27, 2008, 07:49:58 AM »
Sorry to both Nightwalker and Nemo, the routers use dd-wrt, I am remembering software screens for that and a WUSB11. You are both right, the Linksys router software doesn't support adhoc out of the box. I will change the howto.

I'm trying to make this easy for a FEW friends to share files. It may be a dorm, it may be a group of people in new york that have buildings across from each other. It may be people with farms in the middle of no where.

Why can't they just try it?

If people want to go massive then they will have to plan a bit more. I mentioned that. Enough already, why do you think it has to be a huge thing right away? Let it grow.

Let's geek it up, start talking about power levels, DSSS, QPSK and all that so that they get confused and decide to just stick with whatever the big corporations dole out. Good job.

I'm telling you there's lots of factors involved here you can't possibly predict or simulate while sitting in your chair, so people need to just try it. It's called analysis paralysis, it's not going to work so don't even try. It's not perfect from day one, etc...

Oh no, there might be another wireless signal within a mile of you! Give up now!

I've done stuff where you scan and there's all sorts of stations all over and speeds are still good on long distance links. If people are say 500 feet apart and there are other stations causing them to drop to 2M bit/s, so what? That's not good enough? Speeds are going to go up and down, and if they talk to another guy that's 1000 feet away, maybe he will only get DSL speeds. Then once they know this actually works, they might get a $9 10db directional panel antenna and improve things.

People have to learn in steps. Let them do something easy and expand on it.

Let them go borrow some adapters for a day or two and try it across the room, then move further away and see what kind of results they get. A lot of places let you try things and return them in 30 days if you aren't happy.

Most people don't even know adhoc is available to them.

(and I have no problem with either of you posting your own howto on mesh filesharing here, go for it)

Offline Nightwalker_z

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Re: HOWTO: Filesharing via Wifi
« Reply #11 on: July 27, 2008, 04:24:37 PM »
I'm not saying the whole stuff is bad... hell no - just incomplete.
In my opinion, I think that the internet is the better solution, because there are nearly no barriers.
The original statement, that providers might slow down your connections is true, but not a big problem.
Right now they are doing it on a per port basis. But with random ports and an encrypted connection, they could only guess what kind of traffic is flowing. And deep packet inspection is very complicated at high bandwidth, because of delay and stuff.
Just my two cents.....

And because of the geek stuff... you startet the whole modulation and transmission stuff and sorry, most of your statements about it were wrong. I just corrected the statements, because I don't want that the people here learn stuff, that isn't correct. So no complaining :-)

Offline Nemo

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Re: HOWTO: Filesharing via Wifi
« Reply #12 on: July 27, 2008, 07:42:02 PM »
Nemo, thanks and I will try to update my "FAQ", frequently asked questions when you want to know how to P2P over wifi :)

Wifi theory is fun and everything, but there's lots to consider in real world installations.
Don't understand me wrong, Wifi is fun and I like "dirty hacks". As Nightwalker_z already mentioned, your HOWTO is not really a howto with a practical working solution... And as already mentioned some technical details are simply wrong, so please write it when you're not shure about something.

Quote
As for mesh, I was trying to keep it simple for people who just want to get started.
[...]
I say, just try it. Have some fun. See what happens.
[...]
I'm trying to make this easy for a FEW friends to share files. It may be a dorm, it may be a group of people in new york that have buildings across from each other. It may be people with farms in the middle of no where.
[...]
Why can't they just try it?
I'm a geek and I have no problem with new ideas and try and error. As Freifunk people like to say, Wifi is like voodoo and has sometimes unpredictable behaving (theoretical aspects don't work in practise e.g. mesh routing protocols; sometimes it's contrariwise, e.g. links between nodes while theoretically it's impossible).

To prevent many unsuccessful try and error cycles for readers of your HOWTO I recommend to mention Freifunk firmware. The Freifunk people have many experiences in wireless mesh networks. If you want to insert commercial solutions into your howto then you could mention Meraki or others like Locustworld (I haven't any experience with commercial solutions).
I learned much while reading the great books Mesh - Drahtlose Ad-hoc-Netze (german) and Wireless Networking in the Developing World (english, free PDF available).

Quote
And as for power output regulations, do you know anyone who's been taken away lately for putting out a few more mW on wifi?
I know that the Austrian Freifunk people from Funkfeuer in Vienna got controlled and everything was fine.
For me it's simply something like fair use. In my apartement I don't turn my TV as loud as possible: technically it's possible but it makes no sense. In wifi where everyone shares the same ressource it's IMO the same fair use.

Greetings,
Nemo.

Offline scripter

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Re: HOWTO: Filesharing via Wifi
« Reply #13 on: July 28, 2008, 07:15:15 AM »
Nemo, I've added the Freifunk link and edited the howto as best I can to correct the problems. You might want to look it over again.

Offline scripter

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Re: HOWTO: Filesharing via Wifi
« Reply #14 on: August 27, 2008, 05:50:35 AM »
Another reason to go Wifi,

ISU Begins Blocking P2P, Launches 'BirdTrax', Aug 2008
http://www.zeropaid.com/news/9720/ISU+Begins+Blocking+P2P%2C+Launches+%27BirdTrax%27

"Illinois State University" .... "has decided to begin prohibiting the use of P2P and file-sharing applications and services on the campus network." (due to the Higher Education Authorization Act)

The copyright cops are on campus.

The FCC rules for Wifi won't allow universities or other organizations to stop P2P over Wifi.

Universities have no authority or control over the airwaves owned by the People.

They have no cause or jurisdiction to spy on or regulate speed on Wifi networks since stations are mandated to accept any interference from other stations. No excuse that students are interfering with "campus wireless" since the university doesn't own the airwaves, we the people do.

EDIT: More reasons....

It's Official, Comcast to Have 250GB Data Cap Starting Oct 1st
http://www.zeropaid.com/news/9722/It%27s+Official%2C+Comcast+to+Have+250GB+Data+Cap+Starting+Oct+1st
« Last Edit: August 29, 2008, 07:31:12 AM by scripter »