Cant trigger NFS rules if unit was already mounted


Im using Suricata 5.0.3 in Debian 10 and I am trying to trigger nfs alerts. If Suricata is running before I mount an unit it triggers the alerts correctly, but if I mount the unit and then run suricata i cant trigger the nfs alerts.

¿Am i missing something? I didn a mitm to myself to see if something was wrong with nfs but i could see all the data in wireshark.

My rule is:
alert nfs any any -> any 2049 (msg:“NFS: access to testing content”; content:"|74 65 73 74 69 6e 67|";offset:30;sid:1;rev:1;)

The mount steps are:
sudo mount -o vers=3 NFS_SERVER_IP:/exports/lectura /tmp/nfs_exports
cat /tmp/nfs_exports/testing
sudo umount /tmp/nfs_exports/

Regards, Adrian.

Try to create a pcap for both scenarios and see if you can spot the relevant diff. Also you can run the pcaps via -r into suricata again to check if it’s an issue with the packet capture.

But without those details, hard to tell why it won’t hit.