Hello, I was unsuccessful in mounting CephFS with kernel on Ubuntu (it was senta02) today. Here's the command I was using to mount - $ sudo mount -t ceph 172.21.9.32:40886:/ /mnt/kcephfs1 -o name=admin,secret=AQCpa8ld1ahOIhAACPhh2qncfv0LkuI6+kUsEA== mount: mount 172.21.9.32:40886:/ on /mnt/kcephfs1 failed: Connection timed out I got the following message in dmesg logs - [328388.882391] libceph: mon0 172.21.9.32:40886 feature set mismatch, my 107b84a842aca < server's 40107b84a842aca, missing 400000000000000 [328388.894612] libceph: mon0 172.21.9.32:40886 missing required protocol features Port 40886 spoke msgv1, so AFAIS, the command looks fine. I tried 40885 too but I got "Connection timed out" on stdout and "socket closed (con state CONNECTING) in dmesg logs as usual. I also tried running cluster on loopback/localhost and used 127.0.0.1:40917:/ but even that was unsuccessful. To make sure that I am not missing anything I tried the same thing on Fedora 29 and the mount was successful. I've attached logs containing mount commands, dmesg logs and keyring for cluster. I was using this branch to build and run Ceph cluster - https://github.com/rishabh-d-dave/ceph/tree/add-test-for-acls. Thanks, - Rishabh