On Ubuntu 18.04 on my gateway server, I've installed and configured isc-dhcp-server, but it doesn't start up (i.e. it fails to start) if there's nothing connected to enp2s0 after a reboot.
Note it says "Not configured to listen on any interfaces!"
$ service isc-dhcp-server status
● isc-dhcp-server.service - ISC DHCP IPv4 server
Loaded: loaded (/lib/systemd/system/isc-dhcp-server.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Sat 2020-01-18 19:05:34 GMT; 1s ago
Docs: man:dhcpd(8)
Process: 3475 ExecStart=/bin/sh -ec CONFIG_FILE=/etc/dhcp/dhcpd.conf; if [ -f /etc/ltsp/dhcpd.conf ]; then CONFIG_FILE=/etc/ltsp/dhcpd.conf; fi; [ -e /var/lib/dhcp/dhcpd.leases ] || touch /v
Main PID: 3475 (code=exited, status=1/FAILURE)
Jan 18 19:05:34 user-Default-string dhcpd[3475]:
Jan 18 19:05:34 user-Default-string dhcpd[3475]: Not configured to listen on any interfaces!
Jan 18 19:05:34 user-Default-string dhcpd[3475]:
Jan 18 19:05:34 user-Default-string dhcpd[3475]: If you think you have received this message due to a bug rather
Jan 18 19:05:34 user-Default-string dhcpd[3475]: than a configuration issue please read the section on submitting
Jan 18 19:05:34 user-Default-string dhcpd[3475]: bugs on either our web page at www.isc.org or in the README file
Jan 18 19:05:34 user-Default-string dhcpd[3475]: before submitting a bug. These pages explain the proper
Jan 18 19:05:34 user-Default-string dhcpd[3475]: process and the information we find helpful for debugging..
Jan 18 19:05:34 user-Default-string dhcpd[3475]:
Jan 18 19:05:34 user-Default-string dhcpd[3475]: exiting.
My gateway server has two ethernet ports, enp1s0, and enp2s0. I use enp1s0 for internet access via a router, and enp2s0 simply for serving a web app to ethernet-connected laptops. enp2s0 is the one for which the DHCP server assigns IP addresses (for the laptops needing the web app). I want enp1s0 to get a random IP address from the internet-conneted router on the 192.168.1.0 subnet, so that interface is not managed by isc-dhcp-server, only enp2s0.
Here's "ip route" with nothing connected to enp2s0, if that might help...
$ ip route
default via 192.168.1.254 dev enp1s0 proto dhcp metric 100
169.254.0.0/16 dev enp1s0 scope link metric 1000
192.168.1.0/24 dev enp1s0 proto kernel scope link src 192.168.1.76 metric 100
Here's my dhcpd.conf setup:
default-lease-time 600;
max-lease-time 7200;
# The ddns-updates-style parameter controls whether or not the server will
# attempt to do a DNS update when a lease is confirmed. We default to the
# behavior of the version 2 packages ('none', since DHCP v2 didn't
# have support for DDNS.)
ddns-update-style none;
# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
authoritative;
# This is a very basic subnet declaration.
subnet 192.168.2.0 netmask 255.255.255.0 {
range 192.168.2.200 192.168.2.250;
# option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;
option broadcast-address 192.168.2.255;
}
Here's my isc-dhcp-server setup:
# On what interfaces should the DHCP server (dhcpd) serve DHCP requests?
# Separate multiple interfaces with spaces, e.g. "eth0 eth1".
INTERFACESv4="enp2s0"
INTERFACESv6=""
One solution is to restart the isc-dhcp-server after plugging a laptop into enp2s0, but I don't want to have to do that after every reboot, or every time someone plugs in a laptop to enp2s0. The DHCP server works after restarting the service...
$ sudo service isc-dhcp-server restart
$ service isc-dhcp-server status
● isc-dhcp-server.service - ISC DHCP IPv4 server
Loaded: loaded (/lib/systemd/system/isc-dhcp-server.service; enabled; vendor preset: enabled)
Active: active (running) since Sat 2020-01-18 18:22:01 GMT; 14min ago
Docs: man:dhcpd(8)
Main PID: 2437 (dhcpd)
Tasks: 1 (limit: 2016)
CGroup: /system.slice/isc-dhcp-server.service
└─2437 dhcpd -user dhcpd -group dhcpd -f -4 -pf /run/dhcp-server/dhcpd.pid -cf /etc/dhcp/dhcpd.conf enp2s0
Any ideas? I'm sure there's a configuration thing I'm missing, that will solve this problem...
EDIT: Output from command "nmcli connection show lan" (AKA: nmcli c s lan)
$ nmcli connection show lan
connection.id: lan
connection.uuid: 96fbb458-1178-4af2-a1b7-ccce301176e0
connection.stable-id: --
connection.type: 802-3-ethernet
connection.interface-name: enp2s0
connection.autoconnect: yes
connection.autoconnect-priority: 0
connection.autoconnect-retries: -1 (default)
connection.auth-retries: -1
connection.timestamp: 1579379514
connection.read-only: no
connection.permissions: --
connection.zone: --
connection.master: --
connection.slave-type: --
connection.autoconnect-slaves: -1 (default)
connection.secondaries: --
connection.gateway-ping-timeout: 0
connection.metered: unknown
connection.lldp: default
connection.mdns: -1 (default)
802-3-ethernet.port: --
802-3-ethernet.speed: 0
802-3-ethernet.duplex: --
802-3-ethernet.auto-negotiate: no
802-3-ethernet.mac-address: --
802-3-ethernet.cloned-mac-address: --
802-3-ethernet.generate-mac-address-mask:--
802-3-ethernet.mac-address-blacklist: --
802-3-ethernet.mtu: auto
802-3-ethernet.s390-subchannels: --
802-3-ethernet.s390-nettype: --
802-3-ethernet.s390-options: --
802-3-ethernet.wake-on-lan: default
802-3-ethernet.wake-on-lan-password: --
ipv4.method: manual
ipv4.dns: --
ipv4.dns-search: --
ipv4.dns-options: ""
ipv4.dns-priority: 0
ipv4.addresses: 192.168.2.2/24
ipv4.gateway: --
ipv4.routes: --
ipv4.route-metric: -1
ipv4.route-table: 0 (unspec)
ipv4.ignore-auto-routes: no
ipv4.ignore-auto-dns: no
ipv4.dhcp-client-id: --
ipv4.dhcp-timeout: 0 (default)
ipv4.dhcp-send-hostname: yes
ipv4.dhcp-hostname: --
ipv4.dhcp-fqdn: --
ipv4.never-default: no
ipv4.may-fail: yes
ipv4.dad-timeout: -1 (default)
ipv6.method: auto
ipv6.dns: --
ipv6.dns-search: --
ipv6.dns-options: ""
ipv6.dns-priority: 0
ipv6.addresses: --
ipv6.gateway: --
ipv6.routes: --
ipv6.route-metric: -1
ipv6.route-table: 0 (unspec)
ipv6.ignore-auto-routes: no
ipv6.ignore-auto-dns: no
ipv6.never-default: no
ipv6.may-fail: yes
ipv6.ip6-privacy: -1 (unknown)
ipv6.addr-gen-mode: stable-privacy
ipv6.dhcp-send-hostname: yes
ipv6.dhcp-hostname: --
ipv6.token: --
proxy.method: none
proxy.browser-only: no
proxy.pac-url: --
proxy.pac-script: --
EDIT2: Added output from "nmcli -f name,autoconnect connection show"
$ nmcli -f name,autoconnect connection show
NAME AUTOCONNECT
Wired connection 1 yes
lan yes
EDIT3: Added output from "cat /etc/NetworkManager/system-connections/lan"
[connection]
id=lan
uuid=96fbb458-1178-4af2-a1b7-ccce301176e0
type=ethernet
interface-name=enp2s0
permissions=
timestamp=1579379263
[ethernet]
mac-address-blacklist=
[ipv4]
address1=192.168.2.2/24
dns-search=
method=manual
[ipv6]
addr-gen-mode=stable-privacy
dns-search=
method=auto