Forum Discussion

werner_verheyle's avatar
werner_verheyle
Icon for Altocumulus rankAltocumulus
Jul 05, 2019

F5 DNS external monitor

Hi , we are using an F5 DNS (v12.1.2) .   We are now getting request for doing a DNS loadbalalancing for 2 IP's in seperate datacenters. (openshift setups)   Both IP's are accessible via http...
BIG-IP DNS
devops
external monitor
Yoann_Le_Corvi1's avatar
Yoann_Le_Corvi1
Icon for Cumulonimbus rankCumulonimbus

Hi,

First, try to run your CURL test with -vv option to get a full debug of all what Curl sends to the backend to get a 200. Then you can try building a monitor with this info.

I don't quite understand why a CURL with FQDN would work, and not a monitor with Host header, as this is normally the same. It may also be another header (User-Agent, Accept, Content-Type....)

 

Sincerely

cjunior's avatar
cjunior
Icon for Nacreous rankNacreous
Jul 25, 2019

Hi Yoann,

Far as I know, SSL with TLS/SNI isn't possible on the built-in HTTPS monitors, at least on BIGIP version 12.x.

The monitor headers is in OSI Layer 7 and the SNI (server name indication) occurs on Client Hello event during SSL handshake, soon after L4 TCP handshake.

The curl command applies the SNI during the SSL handshake, like as the openssl with parameter "-servername" does.

Please, correct me if am I wrong.

Respectfully