My University information security office does not like rpcbind and will
automatically quarantine any system for which they detect a portmapper
running on an exposed port.
Since I exclusively use NFSv4 I was happy to "learn" that NFSv4 doesn't
require rpcbind any more. For example, here's what it says in the
current RHEL documentation:
"NFS version 4 (NFSv4) works through firewalls and on the Internet, no
longer requires an rpcbind service, supports Access Control Lists
(ACLs), and utilizes stateful operations."
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/managing_file_systems/exporting-nfs-shares_managing-file-systems#introduction-to-nfs_exporting-nfs-shares
I'm using Ubuntu 20.04 rather than RHEL, but the nfs-server service
absolutely will not start if it can't launch rpcbind as a precursor:
-----------------------------
root@helios:~# systemctl stop rpcbind
Warning: Stopping rpcbind.service, but it can still be activated by:
rpcbind.socket
root@helios:~# systemctl mask rpcbind
Created symlink /etc/systemd/system/rpcbind.service → /dev/null.
root@helios:~# systemctl restart nfs-server
Job for nfs-server.service canceled.
root@helios:~# systemctl status nfs-server
● nfs-server.service - NFS server and services
Loaded: loaded (/lib/systemd/system/nfs-server.service; enabled;
vendor preset: enabled)
Drop-In: /run/systemd/generator/nfs-server.service.d
└─order-with-mounts.conf
Active: failed (Result: exit-code) since Fri 2020-09-25 14:21:46
UTC; 10s ago
Process: 3923 ExecStartPre=/usr/sbin/exportfs -r (code=exited,
status=0/SUCCESS)
Process: 3925 ExecStart=/usr/sbin/rpc.nfsd $RPCNFSDARGS
(code=exited, status=1/FAILURE)
Process: 3931 ExecStopPost=/usr/sbin/exportfs -au (code=exited,
status=0/SUCCESS)
Process: 3932 ExecStopPost=/usr/sbin/exportfs -f (code=exited,
status=0/SUCCESS)
Main PID: 3925 (code=exited, status=1/FAILURE)
Sep 25 14:21:46 helios systemd[1]: Starting NFS server and services...
Sep 25 14:21:46 helios rpc.nfsd[3925]: rpc.nfsd: writing fd to kernel
failed: errno 111 (Connection refused)
Sep 25 14:21:46 helios rpc.nfsd[3925]: rpc.nfsd: unable to set any
sockets for nfsd
Sep 25 14:21:46 helios systemd[1]: nfs-server.service: Main process
exited, code=exited, status=1/FAILURE
Sep 25 14:21:46 helios systemd[1]: nfs-server.service: Failed with
result 'exit-code'.
Sep 25 14:21:46 helios systemd[1]: Stopped NFS server and services.
-----------------------------
So, now I'm confused. Does NFSv4 need rpcbind to be running, does it
just need it when it launches, or something else? I made a local copy
of the systemd service file and edited out the rpcbind dependency, so
it's not that.
