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Re: Websockets monitoring


From: Martin Pala
Subject: Re: Websockets monitoring
Date: Wed, 5 Mar 2014 20:56:51 +0100

Hi,

the websocket test is fixed to support non-pong frames sent by server (such as the mentioned chat prompt). Tested with your websocket service, works fine.

You can get the latest code with fix here: https://bitbucket.org/tildeslash/monit/get/master.tar.gz


Regards,
Martin



On 05 Mar 2014, at 13:05, Mehul Ved <address@hidden> wrote:

Sure, you can use it for testing.

On Mar 5, 2014 5:04 PM, Martin Pala <address@hidden> wrote:

Thanks for the trace.

It seems that your server responds with pong (in packet no. 11), but before that, it sends chat text frame with "who" prompt (in packet no. 9):

No.     Time        Source                Destination           Protocol Length Info
      4 0.000384    127.0.0.1             127.0.0.1             HTTP     309    GET / HTTP/1.1

No.     Time        Source                Destination           Protocol Length Info
      6 0.001237    127.0.0.1             127.0.0.1             HTTP     197    HTTP/1.1 101 Switching Protocols

No.     Time        Source                Destination           Protocol Length Info
      8 0.001303    127.0.0.1             127.0.0.1             WebSocket 70     WebSocket Ping [FIN]

WebSocket
    1... .... = Fin: True
    .000 .... = Reserved: 0x00
    .... 1001 = Opcode: Ping (9)
    0... .... = Mask: False
    .000 0000 = Payload length: 0

No.     Time        Source                Destination           Protocol Length Info
      9 0.002225    127.0.0.1             127.0.0.1             WebSocket 75     WebSocket Text [FIN]

    WebSocket
    1... .... = Fin: True
    .000 .... = Reserved: 0x00
    .... 0001 = Opcode: Text (1)
    0... .... = Mask: False
    .000 0101 = Payload length: 5
    Payload
        Text: "who"

No.     Time        Source                Destination           Protocol Length Info
     11 0.003986    127.0.0.1             127.0.0.1             WebSocket 70     WebSocket Pong [FIN]

    WebSocket
    1... .... = Fin: True
    .000 .... = Reserved: 0x00
    .... 1010 = Opcode: Pong (10)
    0... .... = Mask: False
    .000 0000 = Payload length: 0


At this point Monit expects response to its own request, so the protocol test failed.

The server response is OK, we just need to allow server messages (such as this prompt) not related to our own ping request. The websocket.org's service works differently ... it's not chat service, just echo, so it doesn't send any prompt.

Will fix the test. 

Can i use your websocket servis (from the previous email) to verify the test works with it?

Regards,
Martin



On 05 Mar 2014, at 12:13, Mehul Ved <address@hidden> wrote:

Hi Martin,
 It's a custom application developed by us in node.js. I'll speak to my developer and ensure that our application is made RFC compliant. That would be a much cleaner solution.

I'm attaching the pcap file.
________________________________________
From: address@hidden <address@hidden> on behalf of Martin Pala <address@hidden>
Sent: Wednesday, March 05, 2014 3:58 PM
To: This is the general mailing list for monit
Subject: Re: Websockets monitoring

Hi,

it seems that your websocket server doesn't support ping/pong (part of websocket specification: RFC 6455) and instead sent some text frame in response to ping ... either the text frame contains some error description, websocket ping request is prohibited or the server is not RFC 6455 compliant.

The problem can be in the test configuration ... the version 13, origin "http://www.websocket.org" works with the demo echo websocket server operate by websocket.org. Each websocket application has its own version and 13 may be invalid in your case. Also the origin is part of websocket security model and origin "http://www.websocket.org" is basically settings for websocket.org's service ... not general value - but if it was not accepted by the server, it should return 403 error as response to HTTP upgrade request, which it didn't (101 was received, otherwise there will be different error in log).

The websocket.org demo with "location" works for ws://dev.deltamktgresearch.com:10301, but their echo test doesn't use ping - it sends just text frame ... such test is not generic and may fail in other websocket implementations (connect+ping/pong+close should be generic for every RFC compliant server).

We can simplify the test and rely only on websocket connection (http upgrade request) + websocket close ... this should work on all websocket servers, even those which don't support ping/pong.

Please can you get a network trace of the test? You can use for example tcpdump/tshark/wireshark/snoop, tcpdump on the machine where Monit is running:

       tcpdump -s 0 -i any -w websocket.pcap port 10301

If there is also regular traffic which you don't want to expose to mailing list, either filter out only the Monit session packets or send the file directly to me.


Regards,
Martin




On 05 Mar 2014, at 09:32, Mehul Ved <address@hidden> wrote:

Hi Martin,
I tried using the new version of monit but it fails on `monit validate` for websockets

$ which monit
/usr/local/bin/monit

$ monit --version
This is Monit version 5.8
Copyright (C) 2001-2014 Tildeslash Ltd. All Rights Reserved.

The lines I've added:

if failed host dev.deltamktgresearch.com port 10301 protocol websocket
  host "dev.deltamktgresearch.com"
  request "/"
  origin "http://www.websocket.org"
  version 13
  then alert

$ monit validate --verbose
'wsserver' zombie check succeeded [status_flag=0000]
'wsserver' succeeded connecting to INET[dev.deltamktgresearch.com:10301/] via TCP
'wsserver' failed protocol test [WEBSOCKET] at INET[dev.deltamktgresearch.com:10301/] via TCP -- WEBSOCKET: pong error -- opcode 0x1


Using location ws://dev.deltamktgresearch.com:10301 in location box on http://websocket.org works perfectly. It responds with "who" which is correct. Is there a way to set send/expect to check for the correct response?
________________________________________
From: address@hidden <address@hidden> on behalf of Martin Pala <address@hidden>
Sent: Monday, March 03, 2014 2:29 PM
To: This is the general mailing list for monit
Subject: Re: Websockets monitoring

Hi,

we have implemented the websocket protocol test, example usage:

check host websocket.org with address "echo.websocket.org"
  if failed port 80 protocol websocket
    host "echo.websocket.org"
    request "/"
    origin "http://www.websocket.com"
    version 13
  then alert

The test connects to websocket, performs ping/pong test and closes the connection.

If you want to test it, you can get the development Monit version here: https://bitbucket.org/tildeslash/monit/get/master.tar.gz

Compilation:

      tar -xzf master.tar.gz
      cd tildeslash-monit-*
      ./bootstrap && ./configure && make

The monit binary will be in current directory, you can install it to "/usr/local/bin" using "make install"

Regards,
Martin


On 24 Feb 2014, at 07:23, Mehul Ved <address@hidden> wrote:

Hi,
I have a node.js service that works as a websocket server. I am working on monitoring it using monit. I haven't been able to find any information about using websockets with monit either in the group archives or using google search. Has anybody worked on this before?
Is it possible to monitor websockets in monit currently without adding in a websocket client script in between? I can definitely do that but wanted to check if there's a better way to do it without any additional component.
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