Forum Discussion

Ahmed_Galal's avatar
Ahmed_Galal
Icon for Cirrostratus rankCirrostratus
Oct 09, 2019
Solved

Irule to insert source IP in UDP payload

Hi All,   can anyone please provide me with iRule that insert Source IP address in UDP payload?
application delivery
iRules
LTM
  • PeteWhite's avatar
    PeteWhite
    Oct 09, 2019
    when CLIENT_ACCEPTED {
  set payloadLength [UDP::payload length]
  set address [IP::client_addr]
  set addressLength [ string length $address ]
  UDP::payload replace $payloadLength $addressLength $address
}

    You can also use the CLIENT_DATA and SERVER_DATA events and take a look at https://clouddocs.f5.com/api/irules/UDP__payload.html

AndresSolano's avatar
AndresSolano
Icon for Nimbostratus rankNimbostratus
Aug 18, 2021

I tried this iRule for DNS and as soon as I apply the rule in the VIP I stop getting responses, also while collecting captures on the LTM I a "Malformed Packet" on the query from the LTM and the response from the server is a "refused".

Any idea what could be causing this issue? Did you got it working on your side?

PeteWhite's avatar
PeteWhite
Icon for Employee rankEmployee
Aug 19, 2021

This is not for DNS - it inserts the source IP address into the DNS request so it will then not be properly DNS formatted. What do you want to do?

For DNS, you should look at the DNS events and commands: https://clouddocs.f5.com/api/irules/DNS.html