If FastNetMon Advanced suddenly stops working without any error messages in /var/log/fastnetmon/fastnetmon.log then it may be crash due to segmentation fault (segfault) error type.

You can confirm it by running this command:

sudo dmesg 

And then checking output for records like this:

Jul 18 17:21:41 monitor kernel: fastnetmon[30157]: segfault at 0 ip 0000000000445d2f sp 00007f832d861270 error 4 in fastnetmon[400000+90000]

It means some traffic or event caused FastNetMon to execute incorrect memory operation.

In some cases you may see records like this in /var/log/fastnetmon/fastnetmon.log:

[ERROR] Previous run crashed, you can find stack trace below
[ERROR]  0# 0x00000000004831CE in /opt/fastnetmon/app/bin/fastnetmon
 1# 0x00007FBF95594F10
 2# 0x00007FBF9C36C817
 3# 0x00007FBF95594F10
 4# 0x000000000064F03D in /opt/fastnetmon/app/bin/fastnetmon
 5# 0x000000000065D09E in /opt/fastnetmon/app/bin/fastnetmon
 6# 0x000000000084519C in /opt/fastnetmon/app/bin/fastnetmon
 7# 0x000000000084A48F in /opt/fastnetmon/app/bin/fastnetmon
 8# 0x000000000084A8BF in /opt/fastnetmon/app/bin/fastnetmon
 9# 0x000000000084B3D5 in /opt/fastnetmon/app/bin/fastnetmon
10# 0x000000000084BD13 in /opt/fastnetmon/app/bin/fastnetmon
11# 0x00007FBF9C582095
12# 0x00007FBF9C3616DB
13# 0x00007FBF9567761F

Such entries confirm segfault error type too. In such cases FastNetMon was able to intercept error and save basic information which may help to investigate it.

In addition to writing such information FastNetMon installer enables process memory core dumps and they can be found in folder /var/log/core_dumps. They have name in format core.*.*.

You can use them to find out more information about particular crash:

sudo gdb  /opt/fastnetmon/app/bin/fastnetmon  /var/log/core_dumps/core.... <replace by path to latest core dump file>

After it finishes loading it will open interactive command line console and then you need to run following command followed by Enter:


It will show long list of entries and you need to share it with our support team which will be able to review source code and find out root cause and address it.

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