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DoubleDiode 03-19-2013 03:43 AM

Trying to make wlan0 accept incoming connections - Raspbian
 
Hi everyone,

Using my new Raspberry Pi Model A running Raspbian to post this, so proof I have a working outgoing connection. My problem is that I want to be able to SSH to it so I can run it headless. I cannot even ping it from other computers on my LAN. Everything I have read about connecting the Pi reads that once it is connected to the internet, then it can be pinged. SSH is enabled by default in Raspbian and I have checked it is running.

In my /etc/network/interfaces file it is set-up to use a static IP, but changing to dhcp does not help. I can ping other computers on my LAN with success, but he Pi is always unreachable. On my router, wireless isolation is OFF.

iptables is wide open!

iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

Any ideas?

Dave

hamlindsza 03-21-2013 11:48 AM

hmmm...seems strange...could you post the outputs of ifconfig & route -n...it could give us some ideas.

also when you try to ping the pi from another computer, check if the pi is responding the arp request eg. on a windows machine post the output of arp -a

DoubleDiode 03-21-2013 02:59 PM

Thanks for your reply.

On the Pi (192.168.1.121)

pi@raspberrypi ~ $ ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

wlan0 Link encap:Ethernet HWaddr 80:1f:02:82:ad:27
inet addr:192.168.1.121 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:328 errors:0 dropped:341 overruns:0 frame:0
TX packets:422 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:218563 (213.4 KiB) TX bytes:86768 (84.7 KiB)

pi@raspberrypi ~ $ route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.1.199 0.0.0.0 UG 0 0 0 wlan0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 wlan0

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

From Win7 laptop (192.168.1.141)

arp -a

Interface: 192.168.1.141 --- 0xa
Internet Address Physical Address Type
192.168.1.199 00-24-b2-bb-a1-88 dynamic
192.168.1.255 ff-ff-ff-ff-ff-ff static
224.0.0.2 01-00-5e-00-00-02 static
224.0.0.251 01-00-5e-00-00-fb static
224.0.0.252 01-00-5e-00-00-fc static
239.255.255.239 01-00-5e-7f-ff-ef static
239.255.255.250 01-00-5e-7f-ff-fa static
255.255.255.255 ff-ff-ff-ff-ff-ff static

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Thanks again for looking at this for me

Dave

jlinkels 03-21-2013 06:39 PM

How did you connect to wireless anyway? The A doesn't come with a wifi adapter.

You could start TCPDump on the command line and see what happens if a packet arrives on the interface.

jlinkels

DoubleDiode 03-22-2013 08:43 PM

Neither model of Pi comes with wifi, and only the model B has ethernet. I am using a USB dongle as reported by lsusb:

Edimax Technology Co., Ltd EW-7811Un 802.11n Wireless Adapter [Realtek RTL8188CUS]

Repeated pings and attempts to ssh from various computers on my LAN had proved unsuccessful, giving host not found errors. I was going to try tcpdump as you suggested, but it is not installed by default on Raspbian. Now for the bit I do not understand at all, installing tcpdump fixed the issue. I can ssh at last. I have no idea why that made the difference!

Thanks again.

jlinkels 03-22-2013 08:47 PM

Usually I am apt to accept credits for a good advice, but in this case it would really be unjustfied. :D

TCPdump talks on a low-level to the network adapter, maybe that has something to do with it.

Just out of interest, what for project have you intended for your Raspberry?

jlinkels

DoubleDiode 03-23-2013 08:02 PM

I was interested in electronic circuits long before building my first computer from a kit in 1981. My second computer in 1982 was an Acorn Atom, which I really liked as it had a connector at the back to control lights and monitor switches etc. Over 30 years later I can do that sort of thing again with my Pi. My first project for it was to control my SLR camera. A bit of programming and some other electronics has resulted in this:

http://www.youtube.com/watch?v=5qMUEusNzfc

I have a few more timelapses planned!

jlinkels 03-23-2013 10:27 PM

oh, I see. You are just a prehistoric fossile like I am myself. My first program ran with punch cards on an IBM mainframe perhaps as powerful as the Raspberry or even less. I am building an energy analyzer plus datalogger from my Pi. I acquire the data using a USB-DUX. But I purchased the B version with wired ethernet. :D

Good luck.
jlinkels


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