A027 Station Mode with Raspberry-Can’t Establish Socket Connection With Access Point—solved

Objective:

Connect A027 (in station mode) to Raspberry Pi Access Point

Overview:

My A027 works fine in adhoc mode. I have reconfigured it in an attempt to send the AIS/GPS data wirelessly to a Raspberry Pi (RPi) access point (AP) located on the other side of the boat. I have verified that the RPi functions as an AP insofar as I can connect to it wirelessly from another device and display the data sent to it (the RPi) via TCP port 2000. In station mode, the A027 connects (sort of) to the RPi AP but no socket gets established and none of its (the A027’s) AIS/GPS data is ever seen by the RPi AP.

AIS/GPS data can be observed coming out of the A027’s USB port.

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A027 Station Mode Configuration:

Working mode: Station

SSID: vixen_ap

Password: vixen_31

IP Address: 192.168.4.10 (note: Config tool would not allow this field to be left empty, so I don’t see how DHCP could assign the A027 an IP address)

Gateway: 192.168.4.1 (note: Config tool would not allow this field to be left empty, as seen in the Station Mode documentation.)

NetMask: 255.255.255.0

Port: 2000

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RPi (hostname vixenpi) /var/log/syslog output when A027 is powered on:

Dec 26 18:16:18 vixenpi hostapd: wlan0: STA 84:0d:8e:ae:c6:06 IEEE 802.11: disassociated

Dec 26 18:16:18 vixenpi hostapd: wlan0: STA 84:0d:8e:ae:c6:06 IEEE 802.11: associated

Dec 26 18:16:18 vixenpi hostapd: wlan0: STA 84:0d:8e:ae:c6:06 IEEE 802.11: disassociated

Dec 26 18:16:21 vixenpi hostapd: wlan0: STA 84:0d:8e:ae:c6:06 IEEE 802.11: associated

Dec 26 18:16:21 vixenpi hostapd: wlan0: STA 84:0d:8e:ae:c6:06 RADIUS: starting accounting session 92B2B69E7028CFE5

Dec 26 18:16:21 vixenpi hostapd: wlan0: STA 84:0d:8e:ae:c6:06 WPA: pairwise key handshake completed (RSN)

Note: 84:0d:8e:ae:c6:06 is the A027’s MAC address.

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Simple listener program running on the RPi AP (perhaps too much information):

#!/usr/bin/env python

import socket

TCP_HOST =”

TCP_PORT = 2000

tcp_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # TCP

tcp_sock.bind((TCP_HOST, TCP_PORT))

tcp_sock.listen(1)

tcp_conn, addr = tcp_sock.accept()

print ‘Connected by’, addr

tcp_data = tcp_conn.recv(1024)

print ‘from simulated Quark: ‘, tcp_data

tcp_conn.close()

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When this program runs on the RPi AP, netstat shows port 2000 listening for a connection.

pi@vixenpi:~ $ netstat -a |grep 2000

tcp 0 0 0.0.0.0:2000 0.0.0.0:* LISTEN

pi@vixenpi:~ $

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But, the A027 does not connect to it, even after cycling its power while port 2000 is listening on the RPi AP.

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A simple client program running on another host is able to establish a socket on port 2000 and send a message.

Here’s the output on the RPi AP when a simple client program sends a short message on a socket associated with port 2000:

pi@vixenpi:~ $ ./pyserver.py

Connected by (‘192.168.4.2’, 47572)

from simulated Quark: Hello, world

pi@vixenpi:~ $

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Here’s the simple client program that simulated the A027 and sent “Hello, world”:

bob@bob-OptiPlex-580:~/Desktop$ cat pyclient.py

#!/usr/bin/env python

import socket

HOST = ‘192.168.4.1’ #IP address of the RPi AP

PORT = 2000

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

s.connect((HOST, PORT))

s.sendall(‘Hello, world’)

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hostapd.conf on the RPi AP:

pi@vixenpi:~ $ cat /etc/hostapd/hostapd.conf

interface=wlan0

driver=nl80211

ssid=vixen_ap

hw_mode=g

channel=7

wmm_enabled=0

macaddr_acl=0

auth_algs=1

ignore_broadcast_ssid=0

wpa=2

wpa_passphrase=vixen_31

wpa_key_mgmt=WPA-PSK

wpa_pairwise=TKIP

rsn_pairwise=CCMP

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The A027’s static IP address (192.168.4.10) lies outside the range of IP addresses assigned by the RPi AP’s DHCP service.

pi@vixenpi:~ $ cat /etc/dnsmasq.conf

interface=wlan0

dhcp-range=192.168.4.2,192.168.4.5,255.255.255.0,24h

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In Summary:

1) The A027 appears to see the RPi AP and establishes a (partial?) connection with it.

2) “WPA: pairwise key handshake completed (RSN)” seems to indicate that the password validation is successful when the A027 is powered on and the RPi AP is running.

3) No socket gets established on a listening port 2000 (on the RPi AP) when the A027 is powered on.

4) My simple server app (pyserver.py – which creates the listening port 2000) seems adequate to receive data from the A027, but it doesn’t because no socket gets established.

5) It seems the A027 cannot be assigned, via DHCP, an IP address from a router because the Config utility will not allow the IP Address field to be left blank. This probably isn’t relevant to my problem.

Any insight into any of my observations/approach is much appreciated.

I’ve searched for, and read, the forum posts with the word “station” but didn’t see anything that helped.

Cheers and TIA,

–Bob M