SMB/NFS/iSCSI between VLAN<->LAN only works with synproxy enabled

  • Hello,

    I am experiencing a weird issue with VLAN->LAN communication in relation to file sharing protocols (as of now with SMB/CIFS, NFS and iSCSI): In order to create and maintain a successful connection I have to select "State Type: Synproxy" in the advanced settings of the related firewall rule that allows traffic between the two networks.

    The following server systems residing on the LAN segment:

    Synology NAS, hosting SMB, NFSv4 and one iSCSI-Target
    Linux PC, Kernel 5.4.40, hosting SMB.
    Windows 10 Professional, hosting SMB

    Clients on VLANs:

    Linux laptop, kernel 5.6.12, accessing NFS and SMB shares
    Another linux laptop accessing the iSCSI-Target on the NAS
    several iOS-devices using VLC media player using the internal SMB-client to access shares

    Network hardware:

    pfSense 2.4.5 (amd64) on a Protectli FW4B system:
    1x UniFi USW-8-POE 60W
    2x UniFi AP-HD

    What I did so far:

    • When having the firewall pass rule on default values (state type: keep) while trying to access the different kinds of shares, I can see lots of TCP retransmissions in wireshark. In case of iSCSI, the initiator runs into a timeout, mounting a samba-share is quick as normal but listing folder content stalls for minutes but eventually shows the content (otherwise it is not usable), NFS is hanging forever.

    • I already toggled the hardware offloading settings under System -> Advanced -> Networking -> with no difference.

    • Also did a reset of the pfSense settings, created only one VLAN and only the necessary firewall rules -> same effect

    What I plan to test next:

    • Get other hardware and restoring the config
    • Trying out a previous version of pfSense (2.4.4)

    Note: The Protectli pfSense system replaced a Unifi USG 3P gateway device that ran pretty much the same network configuration without any issues. Other applications/services, e.g. HTTP/HTTPS, iperf, DNS, SIP or things like gaming in general seem not affected.

    Advice appreciated.



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