There a number of techniques available to debug SER, the main types fall into two categories :-
Capture the SIP messages
Generate debug information
These types will now be described.
A very useful technique is to look at the actual SIP messages that are produced by SER as seen by other clients on the network. Two tools are commonly used, ethereal ( or the text based equivalent tethereal ) and ngrep. Assuming that you have root access to the sip server, then the syntax for running ethereal is :-
# ethereal port 5060
This will display all packets being sent and received from port 5060 which is the common port used by sip. Added -w file.cap will store the data for future viewing.
SER has the ability to generate a vast amount of information that can be used for debugging. To capture this data, either the stderr file can be redirected, or the program run in foreground. This later technique is achieved by modifying the line fork=no in ser.cfg.
Once the data is being displayed /captured, then the level of detail can be varied by modifying the line debug=4 in ser.cfg higher the number more detail is generated.
Finally the user can add more information by inserting into ser.cfg the command xlog at appropriate points then debug information is required. Please refer to the xlog module README for details.