Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

Forum Discussion

PT2012's avatar
PT2012
Icon for Nimbostratus rankNimbostratus
May 18, 2020

Icall routing path

Hi,   We currently have an icall for crl. When it makes the call to a url, that url has a host entryon the F5 which is a Virtual server on the same F5. The virtual server then forwards to its poo...
iCall
LTM
security
cjunior's avatar
cjunior
Icon for Nacreous rankNacreous
May 21, 2020

Hello,

The BIG-IP device hosts configuration sets the Linux /etc/host file, so it should covers your destination on iCall.

To confirm that, you can generate and check this on a stderr file output.

By the way, I think is better to force the entry on curl command to explicit read the destination what you want to reach:

e.g.

sys icall script mytest_script {
    app-service none
    definition {
        exec curl -v --resolve www.mytest.net:80:10.10.10.10 http://www.mytest.net -io /var/tmp/mytest.content --stderr /var/tmp/mytest.out
    }
    description none
    events none
}
[root@bigipdelta:Active:Standalone] config # cat /var/tmp/mytest.content
HTTP/1.1 302 Object moved
Cache-Control: private
Content-Type: text/html
Location: /default.asp
Server: Microsoft-IIS/10.0
Set-Cookie: ASPSESSIONIDCCRBADCC=JGANCIGDDJDPPPJCGEEABGIF; path=/
Date: Thu, 21 May 2020 19:25:13 GMT
Content-Length: 133
 
<head><title>Object moved</title></head>
<body><h1>Object Moved</h1>This object may be found <a HREF="/default.asp">here</a>.</body>
[root@bigipdelta:Active:Standalone] config # cat /var/tmp/mytest.out
* Rebuilt URL to: http://www.mytest.net/
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0*   Trying 10.10.10.10...
* Connected to www.mytest.net (10.10.10.10) port 80 (#0)
> GET / HTTP/1.1
> Host: www.mytest.net
> User-Agent: curl/7.47.1
> Accept: */*
>
< HTTP/1.1 302 Object moved
< Cache-Control: private
< Content-Type: text/html
< Location: /default.asp
< Server: Microsoft-IIS/10.0
< Set-Cookie: ASPSESSIONIDCCRBADCC=JGANCIGDDJDPPPJCGEEABGIF; path=/
< Date: Thu, 21 May 2020 19:25:13 GMT
< Content-Length: 133
<
{ [133 bytes data]
100   133  100   133    0     0  15414      0 --:--:-- --:--:-- --:--:-- 16625
* Connection #0 to host www.mytest.net left intact

I hope it helps.