Forum Discussion

BOUABRE_343008's avatar
BOUABRE_343008
Icon for Nimbostratus rankNimbostratus
Aug 28, 2018

Monitor problem

Hello

I have a web application that has been inaccessible for some time. But when I change the monitor for an HTTP monitor (monitor by default), services are "OK".

What can be the cause of this problem?

version: BIG-IP 11.6.3.2 monitor(which is a problem): HEAD /jboss/CSS_keepalive.txt HTTP/1.0\r\n Connection: Close\r\n\r\n The monitor is working properly before.

  • tcpdump

    10.55.X.X.80 > 10.X.X.X.40706: Flags [P.], cksum 0xdd52 (correct), seq 1:163, ack 63, win 114, options [nop,nop,TS val 950819840 ecr 1940015649], length 162: HTTP, length: 162

    HTTP/1.1 400 Bad Request
Date: Sun, 26 Aug 2018 00:29:00 GMT
Server: Apache/2.2.15 (Red Hat)
Connection: close
Content-Type: text/html; charset=iso-8859-1
 in slot1/tmm0 lis=

-curl -vk

GET / HTTP/1.1
User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 OpenSSL/1.0.1l zlib/1.2.3 libidn/0.6.5
Host: 10.55.X.X
Accept: */*
HTTP 1.0, assume close after body
HTTP/1.0 503 Service Unavailable
HTTP/1.0 connection set to keep alive!
Connection: Keep-Alive
Content-Length: 1281

Regards

application delivery
BIG-IP
devops
LTM
  • KevinA_246454's avatar
    KevinA_246454
    Aug 28, 2018

    Hi

     

    Is your web server allowing http 1.0 request ? based on the output it certainty does not look http 1.0 is allowed on the webserver . can you test the below

     

    curl --head --http1.0 and compare it against curl --head

     

  • jaikumar_f5's avatar
    jaikumar_f5
    Icon for MVP rankMVP
    Aug 28, 2018

    Was your webserver recently upgraded. If yes, then there is high chance the monitor is broken. As you claim it was working before and now it has stopped, which questions what happened in the servers. I'd guess your webservers were upgraded and post that monitoring failed.

     

    Also the error code 400 bad request logs when the request being sent is having syntax issues. Maybe your send string is having some issues. It could a space or it could be CR/LF anything. You have to figure that out.

     

    I recently encountered this issue, check my thread.

     

  • KevinA_246454's avatar
    KevinA_246454
    Icon for Cirrostratus rankCirrostratus
    Aug 28, 2018

    Hi

     

    Is your web server allowing http 1.0 request ? based on the output it certainty does not look http 1.0 is allowed on the webserver . can you test the below

     

    curl --head --http1.0 and compare it against curl --head

     

    • BOUABRE_343008's avatar
      BOUABRE_343008
      Icon for Nimbostratus rankNimbostratus
      Aug 28, 2018

      Hello

       

      Thank you for your answer, I think an update on the server broke the monitor. I have a 403 error that denies me access to the application

       

      curl --head HTTP/1.1 403 Forbidden Date: Tue, 28 Aug 2018 22:35:29 GMT Server: Apache/2.2.15 (Red Hat) Connection: close Content-Type: text/html; charset=iso-8859-1

       

      curl --head --http1.0 HTTP/1.1 403 Forbidden Date: Tue, 28 Aug 2018 22:34:46 GMT Server: Apache/2.2.15 (Red Hat) Connection: close Content-Type: text/html; charset=iso-8859-1

       

      This error message may mean that you can not access a page because of a missing password.

       

      Regards

       

    • KevinA_246454's avatar
      KevinA_246454
      Icon for Cirrostratus rankCirrostratus
      Aug 29, 2018

      HI Thanks for the feedback, I see i made a typo in the curl request please can you run the below

       

      curl --head --http1.0 curl --head

       

      I must the /jboss uri path :)

       

    • BOUABRE_343008's avatar
      BOUABRE_343008
      Icon for Nimbostratus rankNimbostratus
      Aug 30, 2018

      Hello

       

      Please look

       

      curl --head --http1.0 HTTP/1.1 200 OK Date: Thu, 30 Aug 2018 02:06:26 GMT Server: Apache/2.2.15 (Red Hat) Last-Modified: Wed, 15 Mar 2017 03:20:42 GMT ETag: "61fcb-3-54abc6deb5680" Accept-Ranges: bytes Content-Length: 3 Connection: close Content-Type: text/plain; charset=UTF-8

       

      curl --head HTTP/1.1 200 OK Date: Thu, 30 Aug 2018 02:06:44 GMT Server: Apache/2.2.15 (Red Hat) Last-Modified: Wed, 15 Mar 2017 03:20:42 GMT ETag: "61fcb-3-54abc6deb5680" Accept-Ranges: bytes Content-Length: 3 Connection: close Content-Type: text/plain; charset=UTF-8

       

      Regards

       

  • Stanislas_Piro2's avatar
    Stanislas_Piro2
    Icon for Cumulonimbus rankCumulonimbus
    Aug 30, 2018

    Hi,

    Can you change the monitor send string to 

    HEAD /jboss/CSS_keepalive.txt HTTP/1.0\r\nConnection: Close\r\n\r\n

    Can you try this command line

    (echo -ne "HEAD /jboss/CSS_keepalive.txt HTTP/1.0\r\nConnection: Close\r\n\r\n"; cat) | nc 10.X.X.X 80