All statically assigned addresses, but dhcpcd still runs?

Question

I have a VM (on ESXi 5.1.0) running Debian Wheezy (7.0).

eth0 has a statically assigned address. eth1 was DHCP-assigned, and now I want to make it static.

Here is my old /etc/network/interfaces:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo eth0 eth1
iface lo inet loopback

# The primary network interface
allow-hotplug eth0 eth1
iface eth0 inet static
 address 10.2.1.77
 broadcast 10.2.1.255
 netmask 255.255.255.0
 pointopoint 10.2.1.1

iface eth1 inet dhcp

And here is my new /etc/network/interfaces:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo eth0 eth1
iface lo inet loopback

# The primary network interface
allow-hotplug eth0 eth1
iface eth0 inet static
 address 10.2.1.77
 broadcast 10.2.1.255
 netmask 255.255.255.0
 pointopoint 10.2.1.1

iface eth1 inet static
        address 10.1.0.254
        netmask 255.255.255.0
        gateway 10.1.0.1
        dns-nameservers 8.8.8.8

When I reboot, I can see dhcpcd try to renew my lease for my old DHCP-assigned address, and succeed. And then it overwrites /etc/resolv.conf, which should contain 8.8.8.8 but does not. eth1 does have the correct (static) address, however.

What am I doing wrong here? I don't want to disable dhcpcd outright. In the near future I might switch eth1 back to DHCP, or add a third DHCP-assigned interface.

Solution 1

This is caused by a limitation in dhcpcd5 - it enables DHCP on all interfaces (all or nothing). I fixed this by switching to isc-dhcp-client which is more flexible.

Solution 2

The man page for dhcpcd tells us:

denyinterfaces pattern

         When discovering interfaces, the interface name must not match
         pattern which is a space or comma separated list of patterns
         passed to fnmatch(3).

To stop dhcpcd from operating on an interface(s), you can ask it to leave the interface alone by adding the a line to /etc/dhcpcd.conf.

in the OPs case this would be:

denyinterfaces eth0

This should stop dhcpcd messing with you on that specific interface while leaving dhcpcd enabled. This also lets you keep your interface configuration in /etc/network/interfaces. The other option is using what Ariffer suggested (Using /etc/dhcpcd.conf to do your config instead of /etc/network/interfaces.)

Solution 3

Run (as root):

update-rc.d -f dhcpd remove

If you want to re-enable it in the future,

update-rc.d dhcpd defaults

NOTE: Removing it from rc.d will disable it on all interfaces. Restoring it will enable on all interfaces.

Solution 4

If you are using dhcpcd (the client daemon, most people here are confusing it with DHCP and DHCPd which is different), then add the following text on the bottom of /etc/dhcpcd.conf

static
interface eth0
static ip_address=172.16.0.5/24
static routers=172.16.0.1
static domain_name_servers=8.8.8.8

Of course remember to replace the IP info with your network details.

View more solutions

Comments

[craig65535]

Unfortunately /etc/sysconfig does not exist on Debian. Or at least on my install.

[Goldus]

I should also mention that doing both wont hurt anything unless you plan on adding a NIC that will use DHCP.

[Goldus]

My appologies. I've only ever encountered this problem when using network manager on the command line. After a quick google it appears those files are part of NetworkManager configuration opposed to what you are using.

[craig65535]

So it's all interfaces or no interfaces? Is there a way to use an alternative dhcp client?

[Kruug]

As far as I am aware, yes. I don't know much about Linux, sadly.

[craig65535]

So I was using the dhcpcd5 package. Looks like there are lots of alternatives: dhcpcd, udhcpc, isc-dhcp-client and pump are some of them.

[geerlingguy]

This was helpful reminding me that I needed to do the same thing on wlan0 on my Raspberry Pi when I wanted to switch to manual/static IP on Raspbian Jessie, which runs DHCPd by default. No need to uninstall it completely as long as you configure /etc/dhcpcd.conf correctly.

[Admin]

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