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Forum Discussion

souravkayal_287's avatar
souravkayal_287
Icon for Nimbostratus rankNimbostratus
Aug 01, 2017

Help for irule

set myIpH [format %08x $myIpE] set myIpD1 [expr 0x[substr $myIpH 6 2]] set myIpD2 [expr 0x[substr $myIpH 4 2]] set myIpD3 [expr 0x[substr $myIpH 2 2]] set myIpD4 [expr 0x[substr $myIpH 0 2]] set myIp...
application delivery
BIG-IP
LTM
cjunior's avatar
cjunior
Icon for Nacreous rankNacreous
Aug 01, 2017

Hi,

 

This script part is within a context, so I will not alter or suggest any content here.

 

This way, I think this code snippet is related to a cookie persistence. See:

 

https://support.f5.com/csp/article/K6917

 

So, I think this propose to do the following:

 

Given a cookie value: 1677787402.36895.0000

Catch IP address block
myIpE: 1677787402

Convert value to Hex
set myIpH [format %08x $myIpE] 
Result: 6401010a

Catch Ip address octets
set myIpD1 [expr 0x[substr $myIpH 6 2]]
Result: 0x0a => 10

set myIpD2 [expr 0x[substr $myIpH 4 2]]
Result: 0x01 => 1

set myIpD3 [expr 0x[substr $myIpH 2 2]]
Result: 0x01 -> 1

set myIpD4 [expr 0x[substr $myIpH 0 2]]
Result: 0x64 => 100

Concat to give the server IP address
set myIpD "$myIpD1.$myIpD2.$myIpD3.$myIpD4" 
Result: 10.1.1.100

Write a log on the /var/log/ltm
log local0. "Server Ip address = $myIpD" 
Result: Server Ip address = 10.1.1.100

Select node and port 10.1.1.100:4244 
node $myIpD 4244 

Dispose variables
unset myIpE 
unset myIpH 
unset myIpD1 
unset myIpD2 
unset myIpD3 
unset myIpD4 
unset myIpD 
unset unused

I hope it helps.

 

Regards.