On 23 June 2014 06:24, Avi Cohen <av...@rad.com> wrote: > Hello > In my application (it is a router in the access) I'm initially running > dhclient daemon without any interface specified for dhcp. > Then - on user request - we add interfaces to dhclient.conf on run-time > > I have 3 questions - that I'll appreciate if you can answer
You can read dhclient(8) and dhclient.conf(5) man pages for details. But to summarize ... (You seem to ask 4 questions, so which one will you not appreciate an answer to? :-)) > > 1. Is it possible to append interfaces to an existing dhclient.conf ? > or just to add a new (for example) dhclient.conf-eth1? [BTW - where to > locate this file ?] You can append as many 'interface' statements as you like in the dhclient.conf file. If you want to run with a separate config file for a particular instance of dhclient you can use the '-c' option to specify the non-default file. > > 2. When the daemon will start the dhcp-request for this new interface > ? When you start it. Every interface's dhclient must be started separately. If you start a dhclient without specifying the interface it attempts to find an interface in the 'egress' group. If there is one and only one such interface then dhclient will use it. For other interfaces you must start other instances of dhclient, usually by creating a /etc/hostname.<if> file for that interface. The /etc/hostname.<if> file will be used at system startup or you can 'sh /etc/netstart <if>' as root. > > 3. Our application need to be informed whenever a new IP-address (dhcp) > is assigned for the interface. How to do it ? by polling the dhclient.leases > ? is there a notification from dhclient to our application that we can use > ? The best way to do that is with a program that monitors the routing socket, where you can see all address changes. Alternatively you can monitor the leases file or use the '-L' option to write out the offered and effective lease information if you want complete information on what is being received and used. Some people use the entr port (/usr/ports/sysutils/entr, http://entrproject.org/) to monitor the file(s). > > 4. 4 - if I start the dhclient daemon without interface specified - I > see that it sends dhcp-request for all my exiting interfaces ? why ? how to > disable this behavior and to send request for only > > Specified interfaces ? (but without specifying it in the command line- but > via dhclient.conf ? Now you make me doubt you are running OpenBSD. Our dhclient does not send dhcp-request for all interfaces -- it sends dhcp-requests out one and only one interface. At least for the last 10 years or more. You must specify the interface via the command line, or have the /etc/netstart command build the command line for you from a hostname.<if> file. .... Ken > > > > Regards, > Avi
