NFSv3: Client behind Deny-All-Firewall (dynmic ports to static ports)

[tokia4ever]

Im running a NFSv3 connection between my clients and the RT-N66U with Merlin FW. The problem is, that the clients are behind a Deny-All-Firewall and I have to open some ports to mount correctly.

noob@rockko:/$ rpcinfo -p 192.168.17.2
   program vers proto   port  service
    100000    2   tcp    111  portmapper
    100003    3   udp   2049  nfs
    100003    3   tcp   2049  nfs
    100005    1   udp  35458  mountd
    100005    1   tcp  49688  mountd
    100005    3   udp  35458  mountd
    100005    3   tcp  49688  mountd

The ports 111 and 2049 are static, so no problem But the mount ports like 35458 and 49688 are dynamic and change every time I restart the NFSv3. Is there a possibility to change the dynamic ports to static ones? Which file on the RT-N66U has to be edited?

 

[pachocco1]

My best guess is that the dynamic or ephemeral ports do not require mapping.
Communication is negotiated using the static port assignments and continue on the dynamically assigned port(s). Since this is an existing stateful connection then it should be permitted despite a DENY ANY ANY.