nbd-server - 1:3.21-1+deb11u1 main

Network Block Device (NBD) is a client/server protocol that
emulates a block device (such as a hard disk, a floppy, or a CD-ROM)
over the network, thus giving the system the ability to swap over the
network, or to use raw network disk space for other purposes.
.
However, writing to one Network Block Device from different clients
simultaneously is not recommended, and would probably result in data
loss. If you want multiple clients to share a remote resource, use a
network file system such as NFS or Coda.
.
This package provides the server binary for NBD.