Forum Discussion

Raj_57800's avatar
Raj_57800
Icon for Nimbostratus rankNimbostratus
Apr 15, 2010

Monitor using host header

I am trying to setup a monitor page using host header. It is working when when it is done manually but not when created as a monitor page. Request experts advice. Thanks

 

 

Testing through Telnet

 

 

[root@devbox:Active] ~ telnet 165.28.92.111 80 Trying 165.28.81.111... Connected to 165.28.92.111. Escape character is '^]'. GET /monitor/f5bigip.html HTTP/1.1 Host: dev-apps.test.com:80 Connection: close HTTP/1.1 200 OK Content-Type: text/html Last-Modified: Wed, 14 Apr 2010 20:24:28 GMT Accept-Ranges: bytes ETag: "c877f7b10dcca1:0" Server: Microsoft-IIS/7.0 X-Powered-By: ASP.NET Date: Wed, 14 Apr 2010 21:30:20 GMT Connection: close Content-Length: 67 Development - East Node Up Connection closed by foreign host.

 

 

[root@devbox:Active] ~ telnet 165.28.92.111 80 Trying 165.28.92.111... Connected to 165.28.81.111. Escape character is '^]'. GET /monitor/f5bigip.html HTTP/1.1\r\nHost: dev-apps.test.com:80\r\nConnection: close\r\n HTTP/1.1 400 Bad Request Content-Type: text/html; charset=us-ascii Server: Microsoft-HTTPAPI/2.0 Date: Wed, 14 Apr 2010 21:29:10 GMT Connection: close Content-Length: 311 Bad Request Bad Request HTTP Error 400. The request is badly formed. Connection closed by foreign host.

 

 

My monitor page

 

GET /monitor/f5bigip.html HTTP/1.1\r\nHost: dev-apps.test.com:80\r\nConnection: close\r\n

 

Return string

 

Node Up

 

 

Raj
config
design

6 Replies

Sort By
  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Apr 15, 2010
    Hi Raj,

     

     

    Which LTM version are you running? Can you try removing the \r\n from the end of the send string?

     

     

    GET /monitor/f5bigip.html HTTP/1.1\r\nHost: dev-apps.test.com:80\r\nConnection: close

     

     

    If that works, you can try removing the host header value:

     

     

    GET /monitor/f5bigip.html HTTP/1.1\r\nHost: \r\nConnection: close

     

     

    Aaron
  • smp_86112's avatar
    smp_86112
    Icon for Cirrostratus rankCirrostratus
    Apr 16, 2010
    I think you might need an additional \r\n at the end - like this, as there must be a blank line to terminate the request???

     

     

    GET /monitor/f5bigip.html HTTP/1.1\r\nHost: dev-apps.test.com:80\r\nConnection: close\r\n\r\n
  • Raj_57800's avatar
    Raj_57800
    Icon for Nimbostratus rankNimbostratus
    Apr 16, 2010
    I tried the following formats and ame error.

     

    GET /monitor/f5bigip.html HTTP/1.1\r\nHost: dev-apps.test.com:80\r\nConnection: close\r\n\r\n"

     

     

    GET /monitor/f5bigip.html HTTP/1.1\r\nHost: dev-apps.test.com\r\nConnection: close\r\n\r\n"

     

     

    The interesting part is, I created the following monitor page and applied to the pool. The tcpdump clearly shows the monitor is working.

     

     

    GET /monitor/f5bigip.html HTTP/1.1\r\nHost: dev-apps.test.com:80\r\nConnection: close\r\n\r\n"

     

     

    But when it is done on CLI is when we saw the error.

     

     

    Is it that the CLI does not Recognize syntax ??

     

  • smp_86112's avatar
    smp_86112
    Icon for Cirrostratus rankCirrostratus
    Apr 16, 2010
    I suspect that is the case, since (my understanding is that) Linux interprets "\n" as a CRLF. "\r\n" is used in Windows environments I believe. Maybe TMM is smart enough to figure out the difference, but the Linux kernel is not?
  • L4L7_53191's avatar
    L4L7_53191
    Icon for Nimbostratus rankNimbostratus
    Apr 16, 2010
    I think problem is that you're using telnet for this. Use something like netcat instead - it'll honor the literal \r\n characters and allow you to really mock up what the mointor string is doing. When you're doing it via telnet, every time you're hitting the return key you're appending another \r\n, so you're breaking the request, hence the 400 status.

     

     

    For example, I've copied this from your post above Raj:

     

    echo -e 'GET /monitor/f5bigip.html HTTP/1.1\r\nHost: dev-apps.test.com:80\r\nConnose\r\n\r\n' | nc 10.100.100.10 80

     

     

    ...which produces:

     

     

    HTTP/1.1 200 OK

     

    Date: Fri, 16 Apr 2010 17:44:20 GMT

     

    Connection: close

     

    Content-Type: text/html

     

    Content-Length: 10

     

    Server: TwistedWeb/9.0.0

     

     

    Success! Please post back if netcat doesn't work for you.

     

     

    HTH,

     

    -Matt
  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Apr 16, 2010
    Another thing to consider is that the monitoring daemon, bigd, appends one or two \r\n's to the send string. This has changed slightly over different versions. It consistently causes problems when setting up monitors for a server that strictly enforces the HTTP RFCs for delimiters.

     

     

    SOL2167 provides some good info on this:

     

     

    SOL2167: Constructing HTTP requests for use with the HTTP or HTTPS application health monitor

     

    https://support.f5.com/kb/en-us/solutions/public/2000/100/sol2167.html

     

     

    Aaron