DHCP clients often send hostnames with characters not allowed in DNS such as
spaces.

dhcp-eval should provide a way to rewrite those via hardcoded mechanism (e.g
translate all invalid characters to '-'), or patsubst/regex, or even by
evaluating stdout of execute()

Currently, the only option is something like this:

  if not (option host-name ~~ "^[a-z0-9][a-z0-9\-]+[a-z0-9]$") {
      set new_host-name = concat("host-", binary-to-ascii(16, 8, "", substring(hardware, 1, 6)));
      log(concat("invalid hostname: ", option host-name, " => ", new_host-name));
      ddns-hostname = new_host-name;
  }

which obscures the real DHCP hostname completely.

Dear submitter,

as the package isc-dhcp has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1143544

The version of this package that was in Debian prior to this removal
can still be found using https://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Thorsten Alteholz (the ftpmaster behind the curtain)