Setting the IP with dhcpcd

Question

I have a setup where my system is in the regular home network connected to the router. The router assigns the IP to my device without issues.

I would like to use the same IP every time for my device. Either set it as static or as preferred. This is a fully controlled environment so there should be no problem getting the preferred IP from the DHCP.

Update: I can not change anything on the DHCP server side, I need to come to a solution from the client side. The server is ICS and can not be configured.

Questions

My question is, is this possible via dhcpcd? Can I use a static IP with dhcpcd at all? Or even preferred? I can not avoid the use of dhcpcd because of some unrelated requirements.

Done so far

What I have tried so far is to add these lines to the /etc/dhcpcd.conf file:

interface eth0
        static ip_address=192.168.1.135/24
        static routers=192.168.1.1
        static domain_name_servers=8.8.8.8

This is what the manpages for dhcpcd.conf say:

static value

         Configures a static value.  If you set ip_address then dhcpcd
         will not attempt to obtain a lease and just use the value for the
         address with an infinite lease time.

         Here is an example which configures a static address, routes and
         dns.
               interface eth0
               static ip_address=192.168.0.10/24
               static routers=192.168.0.1
               static domain_name_servers=192.168.0.1

But the problem is that even when I do it like this, I only get to see my device using that IP for a short while, after which it seems to be lost and replaced with another IP most probably assigned via DHCP (it is next in the pool i guess).

Here is my complete dhcpcd.conf file contents:

# Inform the DHCP server of our hostname for DDNS.
hostname

# Use the same DUID + IAID as set in DHCPv6 for DHCPv4 ClientID as per RFC4361.
duid

# Persist interface configuration when dhcpcd exits.
persistent

# Rapid commit support.
# Safe to enable by default because it requires the equivalent option set
# on the server to actually work.
option rapid_commit

# A list of options to request from the DHCP server.
option domain_name_servers, domain_name, domain_search, host_name
option classless_static_routes
# Most distributions have NTP support.
option ntp_servers

# A ServerID is required by RFC2131.
require dhcp_server_identifier

# A hook script is provided to lookup the hostname if not set by the DHCP
# server, but it should not be run by default.
nohook lookup-hostname
noipv4ll

interface eth0
        static ip_address=192.168.1.135/24
        static routers=192.168.1.1
        static domain_name_servers=8.8.8.8

Do I need to add some more options to let DHCP know that I don't need a new IP address or something? Or did I completely misunderstand the topic at hand?

I tried searching for more detailed help online, but either there is not much info on this subject, or more probably, I don't know enough about the topic to perform a valid search.

Any help is appreciated!

Solution 1

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=192.168.1.135/24
static routers=192.168.1.1
static domain_name_servers=8.8.8.8

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

Solution 2

you need to do MAC reservation, like this:

host vnbandk3920.dsdk12.schoollocal {
   hardware ethernet 00:c0:ee:7d:bc:80;
   fixed-address 172.30.176.243;
}

Comments

[Michael Hampton]

You assign reserved IP addresses in the DHCP server, not the client.

[bosnjak]

Hmm, i guess. The problem is that I can not change anything on the DHCP server. What can be done from the client side? (The server is a ICS DHCP server which I can not edit) I updated my question with this info..

[Michael Hampton]

You contact the person who does run the server.

[Michael Hampton]

No. There is not. Asking the same thing over and over will not get you a different answer.

[bosnjak]

I get the feeling there is at least partly misunderstanding, probably because of my lack of knowledge. What is the "static value" option for ? The one from the dhcpcd.conf manpages.

[bosnjak]

This must be done on the server side? I forgot to mention that I don't have the possibility to change anything on DHCP server side, because it is an ICS DHCP. Ill update that to my question.

[Michael Hampton]

This is the way you do it in ISC DHCP. Though, you are still going to have to get the person who runs the server to do it for you.

[bosnjak]

Its not an ISC server, rather the ICS (internet connection sharing) setup. Its the most basic fixed setup so I can't change anything on the server side.

[MariusMatutiae]

@Lawrence I forgot one command in the manual sequence, please take a look at the revised version.