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Wifi between metal buildings


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Hey guys, I've seen a post on this before on the forum but I couldn't find it. Google has some good info on the subject but it's a little vague so I thought I'd ask.

My situation is simple, I am transmitting wifi from a metal building and need to receive in another about 40ft away.

Basically there are three buildings.

A. where the router is located

B. client approx 40 ft away

c. client approx 60-70 ft away

From what I've gathered the best solution is cat6 and an APs but I don't have the option to to run cable.

The other solution I've found is to mount directional antennas on the outside of said buildings. I have a yagi which I tried this morning with my alfa 036H on building B (unmounted to the bulding) and while I was able to pull an IP I was unable to resolve to DNS. The signal strength was showing at 57% but fluctuating. My guess is that the signal was too weak but I find that odd because I've been able to resolve and load pages at lower levels.

Lastly, the buildings are located in a small complex which puts the furthest point (the last building) about 80ft away. The goal is to transmit a strong enough signal to all buildings. Is this possible with a grid antenna on building A and directionals like Yagis on the receiving buildings? Or is am I just S00L unless I run cable?

Thanks in advance.

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Instead of wifi(which is pretty much dead as far as security these days) do both buildings have wired internet access? If so, a LAN/WAN based VPN setup between the two buildings might be more secure, and also offer faster speeds depending on your service provider.

If the wifi router was mounted outside, you'd still need to run cable back inside to wherever it needs to meet the network. Wifi will pretty much die if mounted inside between the two sites if its housed on all sides by metal though unless its really thin or has room for it to leak/pass through any areas of the buildings, but if you had antennas on the roof aimed at each other with enough power and signal from the wireles AP, you might be able to see the other building, but wouldn't count on it without something still wired to a whether proof setup that can reach the inside routers or switches of your network.

Radio can pass through some metal though, which is why your microwave oven, can interfere with your wireless AP's running in the 2.4GHz bands and cause you to lose connections, just like older cordless phones. 5GHz bands aren't affected by microwave ovens as far as I know though, but only way to know if you can get a signal, is try a cantenna or yagi pointed at each other from building to building. Good luck.

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Thanks for the response, yes there is one router inside one of the buildings which is broadcasting to the complex (other two buildings).

The service is for customers and the client doesn't really want to kick out the bucks for vpn service, running cable or providing a myfi service in each building so the antenna option seems to be the most viable. I was leaning twoards that option but wasn't sure which antennas to use or if there were other possible solutions I missed. Thanks again!!

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OpenVPN is free, and you can setup a VM with it preinstalled, not to mention, many operating systems and servers have their own VPN's built in, such as Windows. You can setup a Windows VPN through dial up networking and get a tunnel between the two buildings without purchasing a VPN service. I think the kind of VPN you are thinking of, are ones like Hide My Ass or such, and thats not really what I meant. This would be like a VPN from home laptop provided by work, to a server at work or your workstation at work, which is secured using the Windows VPN or even OpenVPN or such solutions. Even an SSH tunnel between the two buildings over the internet would probably be faster, just depends on your network setup, but just wanted to throw that out there to try first, before beating a dead horse with the wifi directional antennas.

I don't have links handy, but I think Darren even did an episode on how to setup a VPN with windows built in VPN settings, so depending on what you run at the edge of each network, as far as server OS, you should be able to use what you already have installed to create a tunnel between the two locations without spending any money for antennas or such, or third party VPN providers, which wasn't the kind of VPN I was talking about but think you were referring to.

Edited by digip
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I was indeed thinking of the 3rd party VPN service as you mentioned. I've set up ssh before on Linux yes, I didn't consider said solution thinking that I would need an internet connection in each building and a box hosting the VPN service ie. vpn server in the main office/ building. I know any old box can do this but the client only has a simple router, and nothing else.

Let me clarify, (Sorry so wordy and repetative):

What the client wants to do is share the internet connection between three buildings. The modem and router sit inside the main building and the other two buildings have no network infrastructure whatsoever. Think of it as three metal warehouses, which is exactly what we're talking about.

The two buildings with no internet are approximatley between 40-70ft away from the main office with the 3rd building being the furthest.

Right now I'm concentrating on the second building which is only about 40ft away.

So it's a simple problem, It's just that they don't want to spend a lot of money and they haven't given me an exact budget to work with.

At one point I wanted to suggest that they go with MyFi routers in each building or broadband cards if they only want to worry about having specific machines connected to the internet in each office but I worry that there may be connection issues because they will be inside the metal warehouses.

I'm almost tempted to pick up a myfi device to test with but then there is the issue of some providers having better connectivity than others, etc, so it's the element of guess work still exists.

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Ah....that makes more sense now. Yeah, you'd need to setup wifi AP's in all three buildings and have the two either bridged to main buildings network or act as repeaters. Either way, you need to get that signal outside, like rooftop and line of site between them all. I thought each building had its own internet access already, so an interet tunnel to the other building would have been easier, but since they have no connections to the outside world, then no VPN would be of any use, and a mifi, unless you have deep pockets, is 1, going to cap you, usually at about 5GB per month and charge overage fees, and 2, unless you have 4GLTE or better, 3G speeds would be like dial up, and work for one or two machines to maybe read email and surf a few sites, but not going to offer the bandwidth you need. I have a mifi, and its pretty much for emergency use while on the road, and not really going to work, for a full time business setup. However, depending on who your main ISP is at the main building, they may offer a wimax solution and do the antenna and wifi setup for you on the rooftops to help setup the network, but if you can do that yourself, you save some money.

At a minimum, WPA2 of course, but if you can get it working and setup, use a Radius server in combination with WPA2. Will be more secure than WPA2 alone. Few waterproof ebay'd wrt54g's with DDwrt or something like that loaded on them so they all VPN router to router might work if you can mount them outside too and create a secure VPN across each of the buildings in a sort of mesh setup to the main AP.

Whatever you figure out, post your solution. Curious to see what you come up with.

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If you can get the access points on the roof, you shouldn't really need directionals for these distances. I connect to my home access point from inside my barn, and that's 80 to 100 feet away. The metal sides of your buildings is what's killing your signal. If I were to set them up, I'd get some wrt54gl's from a local store, then order a few of these. Set them up as wireless bridges and run the cat5 to your internal wireless or wired network.

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Small question. Any chance the buildings also use the same main powerline, and on the same fase? If so you could try powerline adapters


If thats not possible then wireless on the roof or sides are the only way. But this means wireless linkups between building and prob a other AP or cable inside each building.

Also depending on the building layouts. I like the EnGenius ones. They got build in directional and some got the option to add external entannes. ( omni or directional )

We got 1 costumer would got 2 of these poiting at eachother to form a network bridge. The building are opposite across a road. And the AP are a about 7feet of the ground. ( trucks and busses still get in the way ) but at max power they dont lose connection and no external antenna needed. ( Was actualy first time using these. And we had to luck to try before buy ;) )

2nd time i used them. it was only 1 engenius and 1 normal router. It was at a camping ground. And we got 100+ feet distance out of that. With a few branches in the way. It was stable but not on the max speed. ( 2 of the directionals would fix that. But they didnt want to pay that much, only beeing used 2 months a year )

Ofc like previously said. Use 5Ghz to link buildings ( security through obscurity ) . What the kind see what the cant get ;)

Edited by GuardMoony
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