fwknop-2.6.11 (12/09/2019):
- [server] (Amin Massad) Fixed two bugs in PF handling code - one for
  indefinitely repeating error messages "Did not find expire comment in
  rules list 0" in rule deletion code, and the second where min_exp was
  not computed correctly for min_exp equal to zero. See github issue #295.
- [server] Add ALLOW_ANY_USER_AGENT for ENABLE_SPA_OVER_HTTP mode so that
  fwknopd will accept any User-Agent string coming from the client. By
  default this is disabled, so only SPA packets with a User-Agent string
  that begins with 'Fwknop' will be accepted. Just set this variable to
  'Y' to override this. Then, on the fwknop client command line, use the
  --user-agent option to specify any desired User-Agent string. This
  feature was added to close issue #296 reported by github user
  @fishcreek.