| F5 BIG-IP – Vulnerability!! CVE-2020-5902 – Remote Code Execution (RCE) |
The Traffic Management User Interface (TMUI), also referred to as the Configuration utility, has a Remote Code Execution (RCE) vulnerability in undisclosed pages. (CVE-2020-5902)
This vulnerability allows for unauthenticated attackers, or authenticated users, with network access to the Configuration utility, through the BIG-IP management port and/or self IPs, to execute arbitrary system commands… Read more
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| F5 BIG-IP – Dynamic RDP destination for APM |
Portal access (APM) allows user access internal resources such as servers and computers via Remote Desktop (RDP). There are 3 options to to configure the destination host when configuring the RDP resource:
Hostname and IP address are a fixed destination. In case you need different destinations based on the logged user, you would … Read more
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| F5 BIG-IP – Authentication using active directory |
By default F5 BigIp configuration utility uses local users to authenticate.
But if your enviroment allows it, using another way like Active Directory, LDAP, RADIUS might be very interesting. This post focuses in Active Directory but, anyway, it can point you and be a great help to configure for another type of server.
So, follow these easy steps:
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| F5 BIGIP – Name based reverse proxy (LTM policies) |
F5 BIGIP is a very powerful and versatile product that can be used for several purposed. I started using it as a load balancer. Then I used it to replace the previous SSL VPN portal (and it works perfectly).
Some time ago I decided to start using it as reverse proxy (it was time for my old Microsoft TMG to … Read more
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| F5 BIGIP – Upgrade an active/standby cluster |
Step by step procedure to upgrade an active/standby BIGIP cluster. In this example, I needed to upgrade from BIG IP v13.0.0.0 to v13.1.0.2
Login to https://downloads.f5.com/, search and download the ISO image of the version you want to upgrade to.
As a good sysadmin practice, it is better to export the configuration of both nodes … Read more
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| F5 BIGIP – LTM Policy GUI incorrectly shows conditions with datagroups |
The last F5 BIGIP version 13.1.0.2 (I upgraded from v13.0.0 some days ago – 2018 February) seems to generate a bug with the LTM policies.
Fortunately, the issue is only at the Presentation layer. The LTM policy show the rules conditions always with datagroups. This affects all rules and policies.
Better explained with an example:
If this is a … Read more
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| F5 BIGIP – HTTP header count exceeded maximum allowed count |
Last week we published a new application on our web servers (which are balanced by the F5 BIGIP)
Accessing directly to the servers produced no problem, but when the connection was through the virtual balancing IP of the F5, the application did not work correctly.
Fortunately, monitoring the LTM module logs of the F5 (/var/log/ltm) while the problem … Read more
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| F5 BIGIP – Send logs to custom syslog file |
For debugging purposes (or to simply to organize logs as you prefer) it would be interesting to send certain syslog messages to a custom file instead of the default ones like /var/log/ltm or /var/log/apm
This example shows the way to send syslog messages starting with the string #DEBUG# to the file /var/log/customlog
(You can replace both string and … Read more
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| F5 BIGIP – Bug when using datagroups in LTM policies |
Datagroups can be used in LTM policies to, for example, filter connections based on the client IP address (at least in my BIG-IP v13.0.0)
This is possible by adding a condition like this:
“TCP” – “address” – “matches” – “in datagroup” <DATAGROUP> – at “request” time
(apply traffic on “remote” side of “external” interface)
This works correctly when the … Read more
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| F5 BIGIP – Modify URI path using local traffic policy |
Im using my F5 BIGIP (v13) as reverse proxy to publish some websites by using local traffic policies. But i need to perform a URL rewriting. To be specific, i need to strip a string from the URI path.
It could be done using an IRule:
when HTTP_REQUEST{
if { [string tolower [HTTP::uri] ] starts_with "/path1" } {
HTTP::uri [string 