Dhcpd.conf file location

If you have unexpected behavior you may have a different system running in the background like NetworkManager. Unfortunately the file you have listed contains many errors. You should stick with one of the standard configurations. The eth0 interface was probably not brought up at system boot because it's not listed on the auto line. From man interfaces :. Lines beginning with the word "auto" are used to identify the physical interfaces to be brought up when ifup is run with the -a option.

This option is used by the system boot scripts. Physical interface names should follow the word "auto" on the same line. There can be multiple "auto" stanzas.

The second line is missing the leading symbol to designate the line as a comment. This problem causes the interfaces file to be unreadable by the system.

I spent many hours trying to get my wifi to work before I found this error. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Ask Question. Asked 6 years ago. Active 2 years, 9 months ago. Viewed k times. I am confused and here are several questions: When to use which file? Improve this question. CuriousGuy CuriousGuy 1 1 gold badge 8 8 silver badges 7 7 bronze badges.

Great question and something I was about to ask on raspbian. I happened to find this question after spending an hour of trial and error. I wish I'd found raspberrypi. I think the question should have been asked in comments that how exactly the eth0 failed? What is the ip addr output and systemctl status networking output? Because if the OP tried to do that over ssh and using the eth0 ip to ssh into, then the modified eth0 ip will be assigned as secondary ip to eth0 to keep the ongoing ssh session uninterrupted, I tried to change the eth0 ip as the OP mentioned but sshing through wlan0 and it works and takes preference over dhcp, in my case it was dhclient on Stretch but sshing through eth0, the previous mentioned case takes place.

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If no address is specified, the address will be allocated dynamically if possible , but the host-specific information will still come from the host declaration. These addresses should not also be listed as being available for dynamic assignment. Hosts for which no fixed address is specified can only be booted with DHCP, unless there is an address range on the subnet to which a BOOTP client is connected which has the dynamic-bootp flag set.

The following declarations work in any scope, although you shouldn't use them in group declarations. If you want to send rfc options to such a client, you can set the always-reply-rfc option in that client's host declaration, and the DHCP server will respond with an RFCstyle vendor options field.

This flag can be set in any scope, and will affect all clients covered by that scope. If you don't do this, clients who change subnets will be unable to get a correct IP address until their old lease has expired, which could take quite a long time. If you want to set up a DHCP server so that it is aware of some networks for which it is authoritative and some networks for which it is not, you could declare authority on a per-network-segment basis. The date is specified in the form:.

Where W is the day of the week expressed as a number from zero Sunday to six Saturday. YYYY is the year, including the century. MM is the month expressed as a number from 1 to DD is the day of the month, counting from 1. HH is the hour, from zero to MM is the minute and SS is the second. The use of the server-identifier statement is not recommended: the only reason to use it is to force a value other than the default value to be sent on occasions where the default value would be incorrect.

The default value is the first IP address associated with the physical network interface on which the request arrived. The usual case where the server-identifier statement needs to be sent is when a physical interface has more than one IP address, and the one being sent by default isn't appropriate for some or all clients served by that interface. Another common case is when an alias is defined for the purpose of having a consistent IP address for the DHCP server, and it is desired that the clients use this IP address when contacting the server.

Supplying a value for the dhcp-server-identifier option is equivalent to using the server-identifier statement. An option host-name statement within a host declaration will override the use of the name in the host declaration. DHCP options contain information about a network and the various services it makes available.

DHCP option statements start with the option keyword, followed by an option name, followed by option data, like this:. The contents of the dhcpd. Each lease declaration is identified with the keyword lease followed by the IP address and a block of configuration information within braces.

The starts and ends statements tell you the period when the lease is valid. Each entry is of the form:. The weekday is the numerical value for the day of the week starting with 0 on Sunday, as in this case. The date and time are UCT, not local time. The hardware entry is in the same format as in the dhcpd. The uid entry is a unique identifier for the client, using either an ASCII-string client identifier supplied by the client or the hardware address preceded by hardware type in this example This section gives you some background information that might help explain a few related issues as you create your dhcpd.

If the server knows nothing about the address, it will remain silent, unless the address is incorrect for the network segment to which the client has been attached and the server is authoritative for that network segment, in which case the server will send a DHCPNAK even though it doesn't know about the address.

There may be a host declaration matching the client's identification, and that host declaration contains a fixed-address declaration that is valid for the network segment to which the client is connected. In this case, the DHCP server will never do dynamic address allocation. In this case, the client is required to take the address specified in the host declaration. In that case, the server will take that address and check it to see if the client is still permitted to use it.

If no existing lease is found, or if the client is forbidden to receive the existing lease, then the server will look in the list of address pools for the network segment to which the client is attached for a lease that is not in use and that the client is permitted to have.

It looks through each pool declaration in sequence all range declarations that appear outside of pool declarations are grouped into a single pool with no permit list. If the permit list for the pool allows the client to be allocated an address from that pool, the pool is examined to see if there is an address available.

If so, then the client is tentatively assigned that address. Otherwise, the next pool is tested. If no addresses are found that can be assigned to the client, no response is sent to the client.