I worked on a patch that so far seems to work well. I still need to arrange a few things, but I should be able to submit a patch soon.
The patch will create a additional binary package. isc-dhcp-client pkg : dhclient with DDNS functionality disabled (no random extra ports) isc-dhcp-client-ddns : dhclient with DDNS functionality enabled (with random extra ports) Eric ** Changed in: isc-dhcp (Ubuntu Trusty) Assignee: (unassigned) => Eric Desrochers (slashd) ** Changed in: isc-dhcp (Ubuntu Trusty) Importance: Undecided => Medium ** Changed in: isc-dhcp (Ubuntu Trusty) Status: Confirmed => In Progress -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to isc-dhcp in Ubuntu. https://bugs.launchpad.net/bugs/1176046 Title: isc-dhcp dhclient listens on extra random ports Status in isc-dhcp package in Ubuntu: In Progress Status in isc-dhcp source package in Trusty: In Progress Bug description: Ubuntu 13.04 Server 64-bit. Fresh install. Only one network adapter. dhclient process is listening on two randomly chosen udp ports in addition to the usual port 68. This appears to be a bug in the discovery code for probing information on interfaces in the system. Initial research of the code also suggested omapi, but adding omapi port 9999 to /etc/dhcp/dhclient.conf only opened a forth port with the two random udp ports still enabled. Version of included distro dhclient was 4.2.4. I also tested with the latest isc-dhclient-4.2.5-P1 and got the same results. Debian has the same bug: http://forums.debian.net/viewtopic.php?f=10&t=95273&p=495605#p495605 One impact of these random ports is that security hardening becomes more difficult. The purpose of these random ports and security implications are unknown. Example netstat -lnp output: udp 0 0 0.0.0.0:21117 0.0.0.0:* 2659/dhclient udp 0 0 0.0.0.0:68 0.0.0.0:* 2659/dhclient udp6 0 0 :::45664 :::* 2659/dhclient To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/isc-dhcp/+bug/1176046/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp