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DH's avatar
DH
Icon for Nimbostratus rankNimbostratus
Jan 21, 2020

HTTPS Monitor Questions

How is certificate verification done? Will monitor fail if server has invalid certificate?

 

I am trying to setup a HTTPS Monitor for a website. In Postman I have tested the the 'GET" as follows 'https://XXXXXXX.com/YYYYYYYYYY/ZZZZZZ HTTP/1.1\r\nHost:xxxxxxxxxx.com\r\nConnection: Close\r\n\r\n' It successfully returns a Status of 200 OK

 

I have created the following Monitor in F5. This is a Production site so want to double-check accuracy for monitor before applying.

 

Send String - https://xxxxxxxx.com/yyyyyyyy/zzzzzz HTTP/1.1\r\nHost: xxxxxxxxxx.com\r\nConnection: Close\r\n\r\n

 

Receive String - 200 OK

 

Should the above Monitor work or should I change something in it before testing further on F5?

 

Any comments would be appreciated.

application delivery
BIG-IP
LTM

1 Reply

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  • Rodrigo_Albuque's avatar
    Rodrigo_Albuque
    Icon for MVP rankMVP
    Jan 21, 2020

    Hi DH

    HTTPS Monitor allows you to establish a TLS connection with back-end server.

    By default, no certificate verification is done on BIG-IP so basically if TLS handshake works fine and the receive string is what we configured as expected response, monitor should be marked as UP.

    If you want BIG-IP to verify server's certificate then you can attach a Server SSL profile to your HTTPS monitor and then on Server Authentication, change Server Certificate to Require and add a file with your trusted CAs (who will verify server’s certificate identity) to Trusted Certificate Authorities.

    Trusted Certificate Authorities is a single certificate file (*.crt) with one Root CA or concatenated file with 2 or more Root CAs to confirm server certificate (seen in server-side Certificate message) is trusted by BIG-IP.

    Notice that BIG-IP has a pre-defined bundle (ca-bundle.crt) which contains a list of well-known trusted Root CAs similar to the ones in browsers like Firefox:

    root@(v13)(cfg-sync In Sync)(Peer Time Out of Sync)(/Common)(tmos)# modify ltm profile server-ssl myserverssl2 ca-file ca?
Configuration Items:
 ca-bundle.crt

    If you need to do client authentication, i.e. Server to authenticate BIG-IP as a client, you can additionally add a Certificate and Key to Client Certificate Constrained Delegation section.

    Hope that's clear enough.

    Rodrigo