Thursday, September 21, 2017

GNU Gatekeeper 4.7 (security update)

This version is purely a security update and has no new features. All users are encouraged to update, especially if you use port detection (IgnoreSignaledIPs=1) you should update ASAP.

It has been discovered that GnuGk is vulnerable in some configurations for RTP bleed attacks ( By updating to version 4.7 only the first packets in each media stream influence the media destination.

To further secure your configuration, you can set


to only accept RTP from the same class C network that the call signaling came from. Please beware that this may break a few valid calls where this condition isn't met.

You can download the new version from

Please see the full change log below.

Changes from 4.6 to 4.7
  • fixes for RTP Bleed
  • new switch [Proxy] RestrictRTPSources=IP or Net to limit accepting RTP from the call signal IPs or the respective class C network
  • new switch [Proxy] LegacyPortDetection=1 to keep port detection help for some very old and broken endpoints that will make your gatekeeper vulnerable to RTP Bleed attacks
  • BUGFIX(ProxyChannel.cxx) replace @ip or ip## from aliases when using RedirectCallsToGkIP
  • BUGFIX(ProxyChannel.cxx) better initialization of sendmsg() structs
  • new command line option: now you can use -S instead of --strict (needed on BSD systems)

Monday, September 4, 2017

GNU Gatekeeper 4.6 is out

I'm happy to announce that GNU Gatekeeper version 4.6 has just been

This version has a few new features as well as bug fixes.

New features:
  • least used routing: distribute calls evenly between gateways or MCUs (new switch [RasSrv::ARQFeatures] LeastUsedRouting=1)
  • ability to log to the Unix syslog instead of the trace file (new switch [LogFile] TraceToSyslog=1)
  • new authentication module TwoAliasAuth this is not very safe, but you can use it with endpoints that do not support any password transmission
  • new switch [CTI::MakeCall] Bandwidth= to set the maximum bandwidth  for the calls generated by the GnuGk status port API
  • new status port command: UnregisterEP <ep-id>
  • a number of switches to fine tune TCP keepalives
  • new switch to remove load balancers from the call path ([RoutedMode] RedirectCallsToGkIP=1)

Bug fixes:
  • fixed TCP keepalive for H.460 calls (important!)
  • fixes to port detection for unregistered calls
  • audio fix when GnuGk adds encryption to calls
  • many smaller fixes

You can download the new version from

Please see the full change log below.

Changes from 4.5 to 4.6

  • new switch: [RoutedMode] RedirectCallsToGkIP=1
  • new switches: [RoutedMode] H460KeepAliveMethodH225=, H460KeepAliveMethodH245=, GnuGkTcpKeepAliveMethodH225=, GnuGkTcpKeepAliveMethodH245=
  • BUGFIX(ProxyChannel.cxx) TCP keep-alives for H.460.18 calls weren't always  enabled correctly
  • don't open a status port listener if [Gatekeeper::Main] StatusPort=0
  • BUGFIX(Toolkit.cxx) remove trailing chars before checking for DefaultDomain
  • add callID to H.245 trace messages for easier debugging
  • BUGFIX(ProxyChannel.cxx) forward ReleaseComplete from remaining party while doing call reroute
  • BUGFIX(ProxyChannel.cxx) drop un-en/decryptable RTP packets at end of call  when adding encryption
  • new status port command: UnregisterEP <ep-id>
  • BUGFIX(RasSrv.cxx) remove IPv6 addresses before processing RRQs when IPv6 is not enabled
  • send Facility message as as non-H.460.18 keep-alive for H.225
  • send non-standard H.245 userIndication as non-H.460.18 keep-alive for H.245
  • new switch [RoutedMode] DisableGnuGkH245TcpKeepAlive=1
  • new switch [LogFile] TraceToSyslog=1 to send trace output to syslog (Unix only)
  • BUGFIX(ProxyChannel.cxx) fix port detection for re-opened channels with IgnoreSignaledIPs=1
  • new switch [CTI::MakeCall] Bandwidth= to set the maximum bandwidth for the call
  • new switch [RasSrv::ARQFeatures] LeastUsedRouting=1 to select the least used gateway
  • new authentication module TwoAliasAuth