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Description of problem: DHClient creates an additional listening port in addition to UDP 68 which seems to be a random registered port value. How reproducible: Install dhclient, start the service and perform a netstat -l -u -p and check each of the ports opened by dhclient. Actual results: In this example Opening 60964 port unnecessary : # netstat -panl |grep dhcl udp 0 0 0.0.0.0:60964 0.0.0.0:* 7594/dhclient udp 0 0 0.0.0.0:68 0.0.0.0:* 7594/dhclient Expected results: It should open only 68 port : udp 0 0 0.0.0.0:68 0.0.0.0:* 7594/dhclient Additional info: Additional Info: https://bugzilla.redhat.com/show_bug.cgi?id=962950 http://forums.debian.net/viewtopic.php?f=10&t=95273 http://forums.debian.net/viewtopic.php?f=10&t=95273&p=495605#p495605
As described in bug #962950, comment #5 it's libdns (bind package) what opens these ports and that the only workaround I'm aware of is building dhcpd/dhclient without DDNS support which is most likely not what we want. I can reassign this to bind to further investigate whether it'd be possible to not open these ports in libdns during initialization.
Created attachment 1269039 [details] spawn dns ports on demand later Simple fix delaying creation of those ports. I did not check for possible race conditions much, but it seems to fix the issue.
I think it would be useful for Red Hat to report this bug and the proposed fix to the upstream bug tracker: https://bugs.isc.org/Public/Dist/Display.html?Name=dhcp-public
*** Bug 1486801 has been marked as a duplicate of this bug. ***
(In reply to Charlie Brady from comment #21) > I think it would be useful for Red Hat to report this bug and the proposed > fix to the upstream bug tracker: > > https://bugs.isc.org/Public/Dist/Display.html?Name=dhcp-public Since we follow the rule "upstream first", this was done months ago... https://bugs.isc.org/Public/Bug/Display.html?id=45290 https://source.isc.org/cgi-bin/gitweb.cgi?p=dhcp.git;a=commit;h=ca22af89996483efd820de0084c964fc336ee7c1
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2018:0658