Howto log multiple sftpd instances with their chroot shared via NFS

[Thorsten Glaser]

On Fri, 24 Sep 2021, Stuart Henderson wrote:

> This is amongst the reasons why OpenBSD has the sendsyslog(2) syscall,
> https://man.openbsd.org/sendsyslog.2 - the syslog daemon opens a
> kernel socket to receive those messages, and processes which want to
> write a log entry just call the standard syslog functions which use

Oh, nice.

> The description was for /var/data/chroot/<username>/dev/log i.e. each
> user has their own separate chroot. So this type of approach would
> require mounting a local fs of some sort over the top of each user's dir

This made me curious, and I tried¹ this. It is possible to bind-mount
sockets on Linux iff the target exists as regular file.

sudo touch /var/data/chroot/<username>/dev/log	# but beware of
						# filesystem-based
						# attacks here!
sudo mount --bind /dev/log /var/data/chroot/<username>/dev/log

① I went and began using this technology here:
  https://github.com/mirabilos/shellsnippets/blob/master/posix/debchroot.sh

bye,
//mirabilos
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