Questions[wireless-bridge](server)

I am setting up a wireless LAN between two buildings -- one with Internet and one without. The distance between the buildings is about 900 feet. This goes across a 4 lane street and up/down a hill. It is line-of-sight with a few trees. I don't think they will be in the way. There are no wireless devices. In the building without Internet, there are 2 Windows XP desktops. In the building with Internet, there are are a few more PCs and the server.

I am trying to figure out a few things:

1) How much more beneficial is 5.0 GHz of 2.4 in this scenario?

2) Is WPA2 sufficient encryption or do I need a VPN? The two computers in the building without Internet will be doing 2 things: 1) using RDP to connect to the server. 2) web browsing.

3) The company is not going to want to spend a lot of money on high end gear such as Cisco. Which products should I be looking at instead? I was thinking one wireless router in one building and a range extender bridging device at the other end. At this distance, what are the concerns?

4) Which antennas would you use?

5) Any other comments or thoughts would be greatly appreciated.

I am building a wireless link between two points using Wireless-N standard. To determine the best position of the antennas, there is a signal strength indicator on the antennas. The problem is the link strength doesn't always correspond to link throughput.

I'm looking for an offline version of http://www.speedtest.net or http://www.speakeasy.net/speedtest/ that can do continous monitoring of throughput.

Ideally, I would run this software and monitor increase/decrease of throughput while repositioning the antenna.

The college where I work is wanting to expand our network connection out to the field house building, located about 1/2 to 3/4 mile away from the rest of campus. I'm looking at one of these as a possible solution:

http://www.streakwave.com/Itemdesc.asp?ic=Q-Bridge&eq=&Tp=

I've used them before and been very happy with the results - I just have to keep in mind the throughput limitations (I couldn't run a whole dorm off one of these, for example). But my question here is on the line of sight requirement. In previous uses, line of sight has been perfect. In this case, it's a little less so. There are no buildings in the way, but due to a few trees I can't get a direct view of one building from the other. However, given that I'm only going <1/4 of the rated distance of the connection, is the signal likely to have enough power to establish a good connection?

My understanding of bridging is that it ties together two interfaces at layer 2. I am looking at a Ubiquiti Nanostation2 running OpenWRT that has an ethernet port 'eth0' and a wifi port 'ath0'. The ethernet port (the 'wan' port) is not part of the bridge and the bridge is just a single interface. Can anyone clarify this? - seems very different to Ubuntu.

/etc/config/network:

config 'interface' 'loopback'
    option 'ifname' 'lo'
    option 'proto' 'static'
    option 'ipaddr' '127.0.0.1'
    option 'netmask' '255.0.0.0'

config 'interface' 'wan'
    option 'ifname' 'eth0'
    option 'proto' 'dhcp'

config 'interface' 'wifi'
    option 'ipaddr' '192.168.13.1'
    option 'type' 'bridge'
    option 'proto' 'static'
    option 'netmask' '255.255.255.0'
    option 'ifname' 'wifi0'

One of our new requirements for a product I work on is to support Ethernet-to-wireless bridging. Suppose we have two network interfaces: eth0 and ath0 (we're using the Madwifi driver). What sort of options do I have to allow computers hooked into eth0 to be able to access the wireless network?

The first thing I tried was the brctl utility. This seemed to be exactly what I want. And, on wired networks, it is. But on wireless networks, it didn't quite work. Some Wiresharking revealed that the source MAC of the bridged packet was (correctly) set to a computer behind the bridge. However, the AP, having never seen that MAC associate, would drop the packet. If I enable WDS packets (iwpriv ath0 wds 1), then the packet is sent with the transmitter and receiver addresses, but doesn't seem to be allowed by the AP (it is very old, and we can't change it). Not all APs have to accept WDS, right?

Thus, I'm wondering if we have to do some sort of Ethernet NATing or the like. However, I don't see how it can work -- how can one MAC address be shared amongst n computers? ebtables appears too low level. Simply rewriting MAC addresses on the way out and the way back in makes it so the bridge computer cannot use the network. Plus, how would it know the ultimate destination for an incoming packet? You'd need details from the IP and TCP/UDP layers, at least.