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At the co-working space that I am in, there are a number of wireless access points around. However, there is one that only some of us are able to connect to. We suspect it is because the access point is running on a wireless network that one of the machines does not support.

Out of curiousity, I got to wondering: Is there some command line utility to tell whether a wireless network is a, b, g, or n?

I'm aware that I can get quite a bit of information out of something like iwconfig or airport, but I don't recall it listing the wireless type.

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up vote 2 down vote accepted

The command iwlist scan will tell you, but it won't decode it for you. You have to look at the frequency, channel, and offered speeds to guess what variety of wifi is offered by that access point.

      Cell 11 - Address: 00:24:A8:1B:CC:00
                Frequency:2.442 GHz (Channel 7)
                Quality=28/70  Signal level=-82 dBm  
                Encryption key:off
                Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
                          9 Mb/s; 12 Mb/s; 18 Mb/s
                Bit Rates:24 Mb/s; 36 Mb/s; 48 Mb/s; 54 Mb/s
                Extra: Last beacon: 2328ms ago

That's a 802.11g access point. You can tell because the frequency is 2.4GHz, and the speeds go up to 54Mbs.

802.11n will be on either 2.4GHz or a 5GHz channel, but the speeds offered will be higher.

802.11a will be on a 5GHz channel, but with speeds less than offered by n.

Also pay attention to the security information.

                IE: WPA Version 1
                    Group Cipher : TKIP
                    Pairwise Ciphers (1) : TKIP
                    Authentication Suites (1) : PSK


                IE: IEEE 802.11i/WPA2 Version 1
                    Group Cipher : CCMP
                    Pairwise Ciphers (1) : CCMP
                    Authentication Suites (1) : PSK
                IE: WPA Version 1
                    Group Cipher : CCMP
                    Pairwise Ciphers (1) : CCMP
                    Authentication Suites (1) : PSK

And others. Some wifi stacks don't talk well to some WPA standards.

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This is a really great answer (I tried it at home on my Arch Linux machine), but unfortunately, it doesn't work on Mac. You wouldn't happen to know of the equivalent command in mac, would you? – NT3RP May 14 '12 at 15:52
@NT3RP I don't have a mac to play with, so no I don't. – sysadmin1138 May 14 '12 at 16:55

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