Re: [systemd-devel] Networkd dhcp hostname override
On Wed, 2014-08-13 at 18:55 -0700, Marcel Holtmann wrote: Hi Lennart, Now that networkd can send the systems hostname to the dhcp server, I would find it useful to have an option to override the hostname that gets sent. In my use case, I would like to setup a number of macvlans with different hostnames. Something as simple as [DHCP] SendHostname=true Hostname=foo Sounds useful, though this could just be a single option SendHostname=foobar or so. If not set it sends the system hostname, otherwise the specified hostname. Or something like that. what would this be useful for? Either you send the hostname or you don't. I think what you are looking for is an option to set the Client ID. And when that is set, then that is used. If it not set and SendHostname=true, the hostname is used as Client ID. If SendHostname=false and Client ID is not send, then none of them are send. Typically the send-hostname thing is actually used for DNS updates, where you send the hostname to the DHCP server, which then gives you a lease and sends the hostname + IP to the DNS server, so that your machine is accessible via DNS automatically. I've never heard of it being used as a Client ID, and AFAIK the send hostname and client ID can both be used at the same time. Dan ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Networkd dhcp hostname override
Hi Dan, Now that networkd can send the systems hostname to the dhcp server, I would find it useful to have an option to override the hostname that gets sent. In my use case, I would like to setup a number of macvlans with different hostnames. Something as simple as [DHCP] SendHostname=true Hostname=foo Sounds useful, though this could just be a single option SendHostname=foobar or so. If not set it sends the system hostname, otherwise the specified hostname. Or something like that. what would this be useful for? Either you send the hostname or you don't. I think what you are looking for is an option to set the Client ID. And when that is set, then that is used. If it not set and SendHostname=true, the hostname is used as Client ID. If SendHostname=false and Client ID is not send, then none of them are send. Typically the send-hostname thing is actually used for DNS updates, where you send the hostname to the DHCP server, which then gives you a lease and sends the hostname + IP to the DNS server, so that your machine is accessible via DNS automatically. I've never heard of it being used as a Client ID, and AFAIK the send hostname and client ID can both be used at the same time. this means that allowing to provide a custom hostname that is not set via hostname or hostnamectl makes no sense at all. Since you want to send your actual hostname. So current boolean for SendHostname is the right way to do this. In addition someone might add a ClientId=foo option. Regards Marcel ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Networkd dhcp hostname override
Typically the send-hostname thing is actually used for DNS updates, where you send the hostname to the DHCP server, which then gives you a lease and sends the hostname + IP to the DNS server, so that your machine is accessible via DNS automatically. I've never heard of it being used as a Client ID, and AFAIK the send hostname and client ID can both be used at the same time. Yes. In my network the Host Name dhcp option is used to configure dns. I am attempting to use a single machine to operate several instances of the same server. Therefore I need to bind each server to a unique IP. Currently I use macvlan and dhcpcd to have the dns entries created. this means that allowing to provide a custom hostname that is not set via hostname or hostnamectl makes no sense at all. I will agree that conventionally in the linux world the hostname is for the system itself and not per interface. I suppose it needs to be decided whether it is tolerable for this convention to be bent in networkd. Bridged virtual machines effectively do the same thing, but one could argue it isn't really the same machine. Since you want to send your actual hostname. In this case I don't, I want to specify a custom host name for dhcp on a specific interface. So current boolean for SendHostname is the right way to do this. In addition someone might add a ClientId=foo option. I am not very familiar with the Client ID. It appears to only be useful to change if you wanted multiple dhcp leases with the same hardware address, which I have avoided with macvlans. Regards, Thomas ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Networkd dhcp hostname override
On Thu, 2014-08-14 at 14:29 -0700, Thomas Suckow wrote: Typically the send-hostname thing is actually used for DNS updates, where you send the hostname to the DHCP server, which then gives you a lease and sends the hostname + IP to the DNS server, so that your machine is accessible via DNS automatically. I've never heard of it being used as a Client ID, and AFAIK the send hostname and client ID can both be used at the same time. Yes. In my network the Host Name dhcp option is used to configure dns. I am attempting to use a single machine to operate several instances of the same server. Therefore I need to bind each server to a unique IP. Currently I use macvlan and dhcpcd to have the dns entries created. this means that allowing to provide a custom hostname that is not set via hostname or hostnamectl makes no sense at all. I will agree that conventionally in the linux world the hostname is for the system itself and not per interface. I suppose it needs to be decided whether it is tolerable for this convention to be bent in networkd. Bridged virtual machines effectively do the same thing, but one could argue it isn't really the same machine. Since you want to send your actual hostname. In this case I don't, I want to specify a custom host name for dhcp on a specific interface. So current boolean for SendHostname is the right way to do this. In addition someone might add a ClientId=foo option. I am not very familiar with the Client ID. It appears to only be useful to change if you wanted multiple dhcp leases with the same hardware address, which I have avoided with macvlans. It's used as a general identifier of the client in any situation, so that the server can pass back specific options. Yes, this can be done by looking at the client MAC address, but that's not sufficient in the following cases: 1) non-Ethernet hardware addresses 2) dual-stack clients using DHCPv4 and DHCPv6 3) you change the NIC and want the same options 4) the NIC doesn't have a permanent MAC address The client ID (and on the DHCPv6 side, the DUID) is the single-identifier solution that should really be used instead of the MAC address. Dan ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Networkd dhcp hostname override
It's used as a general identifier of the client in any situation, so that the server can pass back specific options. Yes, this can be done by looking at the client MAC address, but that's not sufficient in the following cases: 1) non-Ethernet hardware addresses 2) dual-stack clients using DHCPv4 and DHCPv6 3) you change the NIC and want the same options 4) the NIC doesn't have a permanent MAC address The client ID (and on the DHCPv6 side, the DUID) is the single-identifier solution that should really be used instead of the MAC address. Touché - Thomas ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Networkd dhcp hostname override
On Thu, 24.07.14 09:53, Thomas Suckow (thomas.suc...@pnnl.gov) wrote: Now that networkd can send the systems hostname to the dhcp server, I would find it useful to have an option to override the hostname that gets sent. In my use case, I would like to setup a number of macvlans with different hostnames. Something as simple as [DHCP] SendHostname=true Hostname=foo Sounds useful, though this could just be a single option SendHostname=foobar or so. If not set it sends the system hostname, otherwise the specified hostname. Or something like that. Added to TODO list. Lennart -- Lennart Poettering, Red Hat ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Networkd dhcp hostname override
Hi Lennart, Now that networkd can send the systems hostname to the dhcp server, I would find it useful to have an option to override the hostname that gets sent. In my use case, I would like to setup a number of macvlans with different hostnames. Something as simple as [DHCP] SendHostname=true Hostname=foo Sounds useful, though this could just be a single option SendHostname=foobar or so. If not set it sends the system hostname, otherwise the specified hostname. Or something like that. what would this be useful for? Either you send the hostname or you don't. I think what you are looking for is an option to set the Client ID. And when that is set, then that is used. If it not set and SendHostname=true, the hostname is used as Client ID. If SendHostname=false and Client ID is not send, then none of them are send. Regards Marcel ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
