F5 is upgrading its customer support chat feature on My.F5.com. Chat support will be unavailable from 6am-10am PST on 1/20/26. Refer to K000159584 for details.

Forum Discussion

EddieJK_26590's avatar
EddieJK_26590
Icon for Nimbostratus rankNimbostratus
May 01, 2017

How do you block empty user-agents?

Hi,   I want to create an iRule to block empty user-agents from hitting our web site instead of letting IIS do it. I've read several posts and came up with this one. Is this ok?   ...
BIG-IP
devops
iRules
David__Pasch's avatar
David__Pasch
Icon for Altostratus rankAltostratus
May 02, 2017

I was not able to test these, but either should get you the results you are looking for:

when HTTP_REQUEST { 
if {[class match [HTTP::header "User-Agent"] equals ""]} {
  reject  
}}

OR

when HTTP_REQUEST {
if { [HTTP::header exists User-Agent]} { if { [HTTP::header User-Agent] equals "" } {
    reject
}}}

Good Luck!