Esp8266 IP Address not reachable after a while

[thehellmaker]

Hi All,
ESP abecomes unavailable after sometime intermittently where it says
Connection to http://192.168.1.4:80 refused
org.apache.http.conn.HttpHostConnectException: Connection to http://192.168.1.4:80 refused

The same happens from the web browser and then it starts working randomly. Checking the logs of the ESP device itself there is no crash.

Am i missing something in the setup of the server which can keep it alive all the time.

I thought this was a webserver problem but it seems like and ESP issue.
Here is the related issue me-no-dev/ESPAsyncWebServer#54

Cheers,
Akash A

[thehellmaker]

A similar issue #1137 was reported on dec 2015

[thehellmaker]

A similar issue also reported in
http://internetofhomethings.com/homethings/?p=426

[thehellmaker]

As mentioned in me-no-dev/ESPAsyncWebServer#54 I have already tried the approach in the link http://www.esp8266.com/viewtopic.php?p=12809 and its still not working.

Now will analyse using wireshark myself

[thehellmaker]

Wireshark is recieving ARP broadcast from the module every second because of the fix.

Here is the packet content.
100 7.995514 Espressi_1a:66:47 Broadcast ARP 42 Gratuitous ARP for 192.168.1.6 (Request)
Frame 100: 42 bytes on wire (336 bits), 42 bytes captured (336 bits) on interface 0
Ethernet II, Src: Espressi_1a:66:47 (5c:cf:7f:1a:66:47), Dst: Broadcast (ff:ff:ff:ff:ff:ff)
Destination: Broadcast (ff:ff:ff:ff:ff:ff)
Address: Broadcast (ff:ff:ff:ff:ff:ff)
.... ..1. .... .... .... .... = LG bit: Locally administered address (this is NOT the factory default)
.... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
Source: Espressi_1a:66:47 (5c:cf:7f:1a:66:47)
Address: Espressi_1a:66:47 (5c:cf:7f:1a:66:47)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: ARP (0x0806)
Address Resolution Protocol (request/gratuitous ARP)
Hardware type: Ethernet (1)
Protocol type: IPv4 (0x0800)
Hardware size: 6
Protocol size: 4
Opcode: request (1)
[Is gratuitous: True]
Sender MAC address: Espressi_1a:66:47 (5c:cf:7f:1a:66:47)
Sender IP address: 192.168.1.6
Target MAC address: 00:00:00_00:00:00 (00:00:00:00:00:00)
Target IP address: 192.168.1.6

[thehellmaker]

For a device to which ARP is responding here is the sequence

1. Request
   1732 208.713855 IntelCor_c5:37:30 Espressi_1a:66:47 ARP 42 Who has 192.168.1.6? Tell 192.168.1.7
2. Response
   1733 208.734013 Espressi_1a:66:47 IntelCor_c5:37:30 ARP 42 192.168.1.6 is at 5c:cf:7f:1a:66:47
3. Request Body

Frame 1732: 42 bytes on wire (336 bits), 42 bytes captured (336 bits) on interface 0
    Interface id: 0 (\Device\NPF_{641ED2C7-4125-43D0-BEF1-205ACE40B627})
    Encapsulation type: Ethernet (1)
    Arrival Time: Jul 26, 2016 21:05:15.359512000 India Standard Time
    [Time shift for this packet: 0.000000000 seconds]
    Epoch Time: 1469547315.359512000 seconds
    [Time delta from previous captured frame: 0.374458000 seconds]
    [Time delta from previous displayed frame: 0.374458000 seconds]
    [Time since reference or first frame: 208.713855000 seconds]
    Frame Number: 1732
    Frame Length: 42 bytes (336 bits)
    Capture Length: 42 bytes (336 bits)
    [Frame is marked: False]
    [Frame is ignored: False]
    [Protocols in frame: eth:ethertype:arp]
    [Coloring Rule Name: ARP]
    [Coloring Rule String: arp]
Ethernet II, Src: IntelCor_c5:37:30 (18:5e:0f:c5:37:30), Dst: Espressi_1a:66:47 (5c:cf:7f:1a:66:47)
    Destination: Espressi_1a:66:47 (5c:cf:7f:1a:66:47)
        Address: Espressi_1a:66:47 (5c:cf:7f:1a:66:47)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Source: IntelCor_c5:37:30 (18:5e:0f:c5:37:30)
        Address: IntelCor_c5:37:30 (18:5e:0f:c5:37:30)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Type: ARP (0x0806)
Address Resolution Protocol (request)
    Hardware type: Ethernet (1)
    Protocol type: IPv4 (0x0800)
    Hardware size: 6
    Protocol size: 4
    Opcode: request (1)
    Sender MAC address: IntelCor_c5:37:30 (18:5e:0f:c5:37:30)
    Sender IP address: 192.168.1.7
    Target MAC address: Espressi_1a:66:47 (5c:cf:7f:1a:66:47)
    Target IP address: 192.168.1.6

1. Response Body

Frame 1733: 42 bytes on wire (336 bits), 42 bytes captured (336 bits) on interface 0
    Interface id: 0 (\Device\NPF_{641ED2C7-4125-43D0-BEF1-205ACE40B627})
    Encapsulation type: Ethernet (1)
    Arrival Time: Jul 26, 2016 21:05:15.379670000 India Standard Time
    [Time shift for this packet: 0.000000000 seconds]
    Epoch Time: 1469547315.379670000 seconds
    [Time delta from previous captured frame: 0.020158000 seconds]
    [Time delta from previous displayed frame: 0.020158000 seconds]
    [Time since reference or first frame: 208.734013000 seconds]
    Frame Number: 1733
    Frame Length: 42 bytes (336 bits)
    Capture Length: 42 bytes (336 bits)
    [Frame is marked: False]
    [Frame is ignored: False]
    [Protocols in frame: eth:ethertype:arp]
    [Coloring Rule Name: ARP]
    [Coloring Rule String: arp]
Ethernet II, Src: Espressi_1a:66:47 (5c:cf:7f:1a:66:47), Dst: IntelCor_c5:37:30 (18:5e:0f:c5:37:30)
    Destination: IntelCor_c5:37:30 (18:5e:0f:c5:37:30)
        Address: IntelCor_c5:37:30 (18:5e:0f:c5:37:30)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Source: Espressi_1a:66:47 (5c:cf:7f:1a:66:47)
        Address: Espressi_1a:66:47 (5c:cf:7f:1a:66:47)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Type: ARP (0x0806)
Address Resolution Protocol (reply)
    Hardware type: Ethernet (1)
    Protocol type: IPv4 (0x0800)
    Hardware size: 6
    Protocol size: 4
    Opcode: reply (2)
    Sender MAC address: Espressi_1a:66:47 (5c:cf:7f:1a:66:47)
    Sender IP address: 192.168.1.6
    Target MAC address: IntelCor_c5:37:30 (18:5e:0f:c5:37:30)
    Target IP address: 192.168.1.7

[thehellmaker]

Found a very interesting thing.
I am using a Windows 7 OS to debug this issue and here are the findings

1. ESP is responding to ARP queries where destination is the ESP MAC address
   1918 151.364565 IntelCor_c5:37:30 Espressi_1a:66:47 ARP 42 Who has 192.168.1.6? Tell 192.168.1.7
1919 151.371335 Espressi_1a:66:47 IntelCor_c5:37:30 ARP 42 192.168.1.6 is at 5c:cf:7f:1a:66:47
2. ESP is not responding to broadcast ARP pings using nmap.
   3459 254.010073 IntelCor_c5:37:30 Broadcast ARP 42 Who has 192.168.1.6? Tell 192.168.1.7

I will look into the arp query responder code in the codebase

[thehellmaker]

Looks like the arp requests are completely handled by lwIP project which is what this project is depenent on.
@me-no-dev looks like you imported the project as dependency 4 months back. And i did a diff with the latest version of the project 1.4.1 of lwIP and seems like some broaddcast functionality was added which is not there in the version imported. Did you import the latest version ?

[me-no-dev]

lwip comes from espressif and not me :) I just tweaked some stuff here and there (not broadcast but multicast). Latest lwip is wip :)

[thehellmaker]

Upgrade to open source Lwip(1.4.1) from 1.3.2 port as suggested by @igrr The module is still responding to ARP requests.. Waiting to see if it stops.

[igrr]

Can you make a diff between 1.3.2 and 1.4.1 in the part which deals with ARP? Maybe we can backport the fix instead of updating all of lwip for now.

[thehellmaker]

Stopped responding to ARP requests on 1.4.1 as well.
The gratuitous ARP that is being sent is not being handled by android devices. Deep diving into the code base to debug further.

51056 1693.352539 Espressi_88:7f:7e Broadcast ARP 42 Gratuitous ARP for 192.168.1.12 (Request)
Frame 51056: 42 bytes on wire (336 bits), 42 bytes captured (336 bits) on interface 0
Ethernet II, Src: Espressi_88:7f:7e (5c:cf:7f:88:7f:7e), Dst: Broadcast (ff:ff:ff:ff:ff:ff)
Address Resolution Protocol (request/gratuitous ARP)

[thehellmaker]

How ever restarting the module takes a new ip address and it starts responding to ARP requests.