Why do I see a Log Split within the Loadmaster L7 Debug Trace Logs
When using content rule with the L7 Debug Trace enabled a log spit can be observed
when the loadmaster logs the use of a Host header in the request.
Why am I seeing a Log Split in the L7 Debug Trace?
2022-04-30T12:00:00+00:00 LMhostname kernel: Host'
Can you explain the meaning behind the log split?
Is this log split a bug?
|Steps to Reproduce:||
Use content rules with a modify URL rule enabled.
Enable the L7 Debug trace:
System Configuration --> Logging Options --> System Log Files --> Debug Options -->
Enable L7 Debug Trace --> Enable Trace
PLEASE NOTE: The "L7 Debug Trace" should only be used for the purposes of troubleshooting and should be disabled immediately afterwards. This is because the "L7 Debug Trace" is a verbose for of debug logging that can consume a lot of resources on the device quickly which can ultimately impact overall performance of the Loadmaster.
2022-04-30T12:00:00+00:00 LMhostname kernel: L7: ffff88882e347cd0: l7_mangle_urireplace '/kemp/test/?id=865143' '/progress-kemp/test/?id=865143' ' HTTP/1.1
|Cause:||For the specific log message mentioned (kernel: Host'), it can happen that under certain circumstances, one of the three strings logged will contain a newline or CRLF sequence and wrap to a second line.|
HTTP/1.1 - Feature Description
By default, the LoadMaster uses HTTP/1.0. However you may opt to use HTTP/1.1 which will operate more efficiently.
This affect Loadmaster to real server connections.
HTTP/1.1 Host - Feature Description
This field will only be visible if 'Use HTTP/1.1' is selected under the real server health check options.
When using HTTP/1.1 checking, the Real Servers require a hostname to be supplied in each request. If no value is set, then this value is the IP address of the Virtual Service.
'HTTP/1.1 Host' - L7 Debug Log
For the specific log message mentioned (kernel: Host'), it can happen that under certain circumstances, one of the three strings logged will contain a newline or CRLF sequence and wrap to a second line.
2022-04-30T12:00:00+00:00 LMhostname kernel: L7: ffff88882e347cd0: l7_mangle_urireplace '/kemp/test/?id=865143' '/progress-kemp/test/?id=865143' ' HTTP/1.1 2022-04-30T12:00:00+00:00 LMhostname kernel: Host'
String 1: '/kemp/test/?id=865143'
String 2: '/progress-kemp/test/?id=865143'
String 3: ' HTTP/1.1 Host'
This has been recognized as a issue and is being worked under the enhancement ID: LM-1278
Please referrer to the LoadMaster firmware release notes for specific versions of LoadMaster OS in order to verify if the fix has been included.
LoadMaster firmware release notes can be accessed here.
NOTE: Generally speaking we would discourage any non-troubleshooting processing of debug logs