I have tried both subinterfaces and secondary ip address route and neither are working for isc-dhcp-server. It is refusing to pull the proper IP's. I am using Debian 8 Jessie and ISC-DHCP-SERVER 4.3.1. My /etc/network/interfaces ## Corporate Network auto eth0 allow-hotplug eth0 iface eth0 inet manual ## New Subnet auto eth0:0 allow-hotplug eth0:0 iface eth0:0 inet static address 10.0.0.2 gateway 10.0.0.1 netmask 255.255.0.0 dns-nameservers 127.0.0.1 10.0.0.3 dns-search example.net dns-domain example.net ## Old Subnet auto eth0:1 allow-hotplug eth0:1 iface eth0:1 inet static address 10.136.136.253 netmask 255.255.255.0 ifconfig eth0 Link encap:Ethernet HWaddr b8:27:eb:c0:59:e5 inet6 addr: fe80::ba27:ebff:fec0:59e5/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:26688 errors:0 dropped:69 overruns:0 frame:0 TX packets:7301 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:7174565 (6.8 MiB) TX bytes:1286716 (1.2 MiB) eth0:0 Link encap:Ethernet HWaddr b8:27:eb:c0:59:e5 inet addr:10.0.0.2 Bcast:10.0.255.255 Mask:255.255.0.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 eth0:1 Link encap:Ethernet HWaddr b8:27:eb:c0:59:e5 inet addr:10.136.136.253 Bcast:10.136.136.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 ip add 2: eth0: mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether b8:27:eb:c0:59:e5 brd ff:ff:ff:ff:ff:ff inet 10.0.0.2/16 brd 10.0.255.255 scope global eth0:0 valid_lft forever preferred_lft forever inet 10.136.136.253/24 brd 10.248.28.255 scope global eth0:1 valid_lft forever preferred_lft forever inet6 fe80::ba27:ebff:fec0:59e5/64 scope link valid_lft forever preferred_lft forever /var/log/syslog when starting isc-dhcp-server Aug 12 09:48:20 ns01 dhcpd: Wrote 0 deleted host decls to leases file. Aug 12 09:48:20 ns01 dhcpd: Wrote 0 new dynamic host decls to leases file. Aug 12 09:48:20 ns01 dhcpd: Wrote 5544 leases to leases file. Aug 12 09:48:21 ns01 dhcpd: Aug 12 09:48:21 ns01 dhcpd: No subnet declaration for eth0:1 (no IPv4 addresses). Aug 12 09:48:21 ns01 dhcpd: ** Ignoring requests on eth0:1. If this is not what Aug 12 09:48:21 ns01 dhcpd: you want, please write a subnet declaration Aug 12 09:48:21 ns01 dhcpd: in your dhcpd.conf file for the network segment Aug 12 09:48:21 ns01 dhcpd: to which interface eth0:1 is attached. ** Aug 12 09:48:21 ns01 dhcpd: Aug 12 09:48:21 ns01 dhcpd: Aug 12 09:48:21 ns01 dhcpd: No subnet declaration for eth0:0 (no IPv4 addresses). Aug 12 09:48:21 ns01 dhcpd: ** Ignoring requests on eth0:0. If this is not what Aug 12 09:48:21 ns01 dhcpd: you want, please write a subnet declaration Aug 12 09:48:21 ns01 dhcpd: in your dhcpd.conf file for the network segment Aug 12 09:48:21 ns01 dhcpd: to which interface eth0:0 is attached. ** Aug 12 09:48:21 ns01 dhcpd: Aug 12 09:48:21 ns01 dhcpd: failover peer failover: I move from normal to startup Aug 12 09:48:21 ns01 dhcpd: Server starting service.

I'm running ISC DHCPd on Raspbian. I want to set up my server so that all addresses in 192.168.0.0/24 are static leases, and all in 192.168.1.0/24 are dynamic leases. I'd like the two to share the 192.168.0.0/23 subnet. **Clarification:** Basically, I want a single DHCP server to handle DHCP for the entire 192.168.0.0/23 subnet. If a device that requests an IP has a host entry defined in dhcpd.conf, it will assign it the IP address that is specified. If it does not, it will assign an address in the range 192.168.1.2 - 192.168.1.254. For simplicity, I have limited all of my static leases to reside in the range 192.168.0.2 - 192.168.0.254. I have my server configured as so: option domain-name "home"; option domain-name-servers 192.168.0.3; default-lease-time 600; max-lease-time 7200; ddns-update-style none; authoritative; host mightyturing{ hardware ethernet 10:bf:48:87:74:a2; fixed-address 192.168.0.64; } host beastnugget{ hardware ethernet 34:e6:d7:52:1e:e4; fixed-address 192.168.0.65; } host ... (about 50 more static leases) subnet 192.168.1.0 netmask 255.255.255.0 { option routers 192.168.0.1; option broadcast-address 192.168.1.255; option domain-name-servers 192.168.0.3, 1.1.1.1; option domain-name "home"; option subnet-mask 255.255.254.0; ddns-updates off; } When I try to start the service it whines: Nov 17 17:45:26 raspberrypi dhcpd: DHCPREQUEST for 192.168.0.64 from 10:bf:48:87:74:a2 via eth0 Nov 17 17:45:26 raspberrypi dhcpd: DHCPACK on 192.168.0.64 to 10:bf:48:87:74:a2 via eth0 Nov 17 17:45:59 raspberrypi dhcpd: Dynamic and static leases present for 192.168.0.64. Nov 17 17:45:59 raspberrypi dhcpd: Remove host declaration mightyturing or remove 192.168.0.64 Nov 17 17:45:59 raspberrypi dhcpd: from the dynamic address pool for 192.168.0.0/23 ... and since my lease pool is 192.168.1.0/24... I'm pretty sure that means that 192.168.0.64 is not in the pool. So why is ISC not recognizing this? Why is it complaining about a range that I have not instructed it to issue dynamic IPs for? **Also:** When I change the range to issue dynamic IPs on the 10.0.0.0/24 range (to test ISC's sanity), but keep the static leases in 192.168.0.0/24, it still complains about 192.168.0.0/23 so what is going on? Where, precisely, did I ask it to hand out 192.168.0.0/23 addresses? option domain-name "home"; option domain-name-servers 192.168.0.3; default-lease-time 600; max-lease-time 7200; ddns-update-style none; authoritative; host mightyturing{ hardware ethernet 10:bf:48:87:74:a2; fixed-address 192.168.0.64; } host beastnugget{ hardware ethernet 34:e6:d7:52:1e:e4; fixed-address 192.168.0.65; } subnet 10.0.0.0 netmask 255.255.255.254 { option routers 10.0.0.1; option broadcast-address 10.0.0.255; option domain-name-servers 1.1.1.1; option domain-name "home"; option subnet-mask 255.255.255.0; ddns-updates off; }

We have a dhcp server (linux) to serve a few printers Nuc devices. It is configured to assign IPv4 address, gateway, dns1, dns2, dns3, dns4, ntp1, ntp2, dns-search domains, domain suffix and hostname based on the pool. 1 Pool: Printers 2 Pool: TV (Nuc devices) 3 Pool: guests Each pool has an entry to assign a host name to a device like [p|tv|g]-lvl(n)-[NNN]. For the tv pool we have the following hostname pattern: tv-lvl(n)-[NNN] where (n) is the the floor level and [NNN] the last 1 to 3 digits of the IP address (ex.: tv-lvl1-180. While installing linux we don't confiugre hostname and leave it to the default (localhost), then with a shell script we configure the network connection to get DHCP settings as configured from the dchp server. However the hostname of the device remains localhost. Here is what the script does(Please note not the actual code): nmcli connection modify id 'Wired Connection 1' ipv4.addresses "" nmcli connection modify id 'Wired Connection 1' ipv4.gateway "" nmcli connection modify id 'Wired Connection 1' ipv4.dns "" nmcli connection modify id 'Wired Connection 1' ipv4.dns-search "" nmcli connection modify id 'Wired Connection 1' ipv4.method auto nmcli connection modify id 'Wired Connection 1' autoconnect yes nmcli connection modify id 'Wired Connection 1' hostname.from-dhcp true nmcli connection modify id 'Wired Connection 1' hostname.only-from-default true nmcli connection modify id 'Wired Connection 1' hostname.from-dns-lookup true then we reboot and the device get the correct IP settings. I can ping the device from anywhere like ping tv-lvl1-180 with no issues and I can even ssh the device ssh tv-lvl1-180 however the prompt remains as: user@localhost: ~$ How to make the assigned hostname the actual hostname of the device? From user@localhost: ~$ to user@tv-lvl1-180: ~$ In case that the following is needed here is what we get when we run: user@localhost:~$ hostname localhost user@localhost:~$ hostnamectl Static hostname: localhost Pretty hostname: linuxmint <- We changed it for other reasons. Icon name: computer-desktop [...] user@localhost:~$ cat /etc/hostname localhost user@localhost:~$

_My task_: Configure and run Access Point (AP) on the tablet (x86) with Linux mint with access from devices connected to the created AP. ##### Background as additional information (but this is not the topic of question, *real question at the end of description*): - Some measurement devices must connect to this tablet via AP and send data to it throw tcp socket. #### I have done the next parts: --- ## 1. Created the Virtual WiFi interface - the created intefce works as isolated (not bridged, like a router) All the scripts are provided for the physical WiFi interface wlp1s0 I created the virtual interface with the name wlp1s0_ap - Created a unit (service) file as /lib/systemd/system/wireless-device@.service

[Unit]
Description=Create virtual wireless interface
Requires=sys-subsystem-net-devices-wlp1s0.device
#After=network.target
After=sys-subsystem-net-devices-wlp1s0.device
[Service]
Type=oneshot
#ExecStart=/usr/sbin/iw dev wlp1s0 interface add %I type __ap  addr "00:0c:e3:6f:78:ee"
ExecStart=/usr/sbin/iw dev wlp1s0 interface add %I type managed addr "00:0c:e3:6f:78:ee"
#ExecStart=/usr/bin/iw dev wlan0 interface add wlp1s0_ap type __ap addr "00:0c:e3:6f:78:ee"
[Install]
WantedBy=multi-user.target

- Then run systemctl enable wireless-device@wlp1s0_ap.service - Reboot the PC --- ## 2. Added the new virtual interface into ignored ones for the **NetworkManager** **edit:**

sudo nano /etc/NetworkManager/NetworkManager.conf

by adding **wlp1s0_ap** created interface into _unmanaged-devices_ section (**NB!** append to existing ones)

[keyfile]
unmanaged-devices=interface-name:wlp1s0_ap

run

sudo nmcli general reload

--- ## 3. Configured hostapd I called the AP as EVT with password ******. More details are below. - install hostapd - sudo apt install hostapd - edit the file sudo nano /etc/default/hostapd - current version is below

DAEMON_CONF="/etc/hostapd/hostapd.conf"

- edit the configuration file (below is the current variant): - sudo nano /etc/hostapd/hostapd.conf

interface=wlp1s0_ap
driver=nl80211
country_code=EE

ssid=EVT
wpa_passphrase=****

hw_mode=g
channel=10

wpa=2
wpa_key_mgmt=WPA-PSK

wpa_pairwise=TKIP
rsn_pairwise=CCMP
auth_algs=1
macaddr_acl=0
ieee80211n=1

- the daemon is started as - sudo systemctl start hostapd --- ## 4. Configured DHCP server Fro the DHCP server isc-dhcp-server is selected. ### _isc-dhcp-server_ configuration - install: sudo apt install isc-dhcp-server - edit the file - sudo nano /etc/dhcp/dhcpd.conf, (below is the current variant):

# dhcpd.conf

#INTERFACES="wlp1s0_ap"

option domain-name "etv.org";
option domain-name-servers 192.168.1.2, 192.168.1.3;

default-lease-time 86400;
max-lease-time 604800;

ddns-update-style none;

authoritative;

subnet 192.168.1.0 netmask 255.255.255.0 {
        interface wlp1s0_ap;
        ## dhcp start  and end IP range ##
        range 192.168.1.100 192.168.1.200;
        option subnet-mask 255.255.255.0;     ## subnet
        option broadcast-address 192.168.1.255; ## broadcast
        option routers 192.168.1.254; ## router IP
}

The daemon is started as service isc-dhcp-server start --- ## 5. Assigned static IP address for the created virtual interface I modified the file to assign the IP 192.168.1.111 to the interface wlp1s0_ap:

sudo nano /etc/network/interfaces

the content of the /etc/network/interfaces file is

auto lo
iface lo inet loopback

auto wlp1s0_ap
iface wlp1s0_ap inet static
  address 192.168.1.111
  netmask 255.255.255.0
  gateway 192.168.1.0
  broadcast 192.168.1.255
  dns-nameservers 192.168.1.2,192.168.1.3

--- ### The parts described above are working and I can connect to the AP. ### ifconfig listing:

lo: flags=73  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 1386  bytes 149889 (149.8 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1386  bytes 149889 (149.8 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlp1s0: flags=4163  mtu 1500
        inet 172.20.92.22  netmask 255.255.255.0  broadcast 172.20.92.255
        inet6 fe80::9ea9:58d3:aa31:b7e9  prefixlen 64  scopeid 0x20
        ether 00:0c:e3:6f:78:ed  txqueuelen 1000  (Ethernet)
        RX packets 1111808  bytes 125498550 (125.4 MB)
        RX errors 0  dropped 7507  overruns 0  frame 0
        TX packets 23673  bytes 3070974 (3.0 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlp1s0_ap: flags=4163  mtu 1500
        inet 192.168.1.111  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::20c:e3ff:fe6f:78ee  prefixlen 64  scopeid 0x20
        ether 00:0c:e3:6f:78:ee  txqueuelen 1000  (Ethernet)
        RX packets 808  bytes 124999 (124.9 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 893  bytes 155057 (155.0 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

# Problem: **However I cannot communicate with this Tablet** For example, ping to the assigned IP ping 192.168.1.111 gives the next response:

PING 192.168.1.111 (192.168.1.111) 56(84) bytes of data.
From 192.168.1.101 icmp_seq=1 Destination Host Unreachable
From 192.168.1.101 icmp_seq=2 Destination Host Unreachable
From 192.168.1.101 icmp_seq=3 Destination Host Unreachable
From 192.168.1.101 icmp_seq=4 Destination Host Unreachable
^C
--- 192.168.1.111 ping statistics ---
5 packets transmitted, 0 received, +4 errors, 100% packet loss, time 4065ms

**telnet** output:

~$ telnet 192.168.1.111
Trying 192.168.1.111...
telnet: Unable to connect to remote host: No route to host

The questions: 1. What I missed? 2. How to configure the access to the Tablet on which hostapd + DHCP are running?

I have isc-dhcp-4.2.5 server and client installed on two CentOS-7.4 boxes. I know this is quite old distro, but I can't change it for various reasons. Dhcp server configuration: option domain-name "mydomain.org"; option domain-name-servers ns1.mydomain.org, ns2.mydomain.org; default-lease-time 600; max-lease-time 7200; log-facility local7; option space myspace; option myspace.node-ip code 1 = ip-address; # Tell the server to return vendor-specific information option dhcp-parameter-request-list 43; class "vendor-classes" { match option vendor-class-identifier; } subclass "vendor-classes" "my-vendor-class-ID" { vendor-option-space myspace; option myspace.node-ip 10.5.6.7; } subnet 10.0.0.0 netmask 255.255.255.0 { range 10.0.0.50 10.0.0.60; option routers 10.0.0.254; } Dhcp client configuration: interface "veth0" { send dhcp-client-identifier "my-client-ID"; send vendor-class-identifier "my-vendor-class-ID"; send dhcp-lease-time 900; } I'm seeing two problems: 1. The client fails to send options dhcp-client-identifier and vendor-class-identifier, tcpdump does not show those 2. The server fails to send Option-43 It's almost that this version does not support dhcp-client-identifier and vendor-class-identifier at all? What am I doing wrong? PS. Latest ISC-dhcp (ver. 4.4.2) built from https://gitlab.isc.org/isc-projects/dhcp has no these problems.

I'm trying to create a PXE server on my raspberry pi, but if I try to boot, the client shows the Error "Failed to load ldlinux.c32". This is my folder structure of the tftp folder: Here is my pxelinux.cfg configuration: DEFAULT vesamenu.c32 PROMPT 0 TIMEOUT 300 MENU TITLE PXE Network Boot Menu LABEL local MENU LABEL BOOT FROM LOCAL DISK MENU DEFAULT LOCALBOOT 0 LABEL memtest MENU LABEL memtest86+ v4.20 KERNEL memtest And this is my DHCP configuration: subnet 10.0.0.0 netmask 255.255.252.0 { option ntp-servers de.pool.ntp.org; option domain-name ".pudding.net"; option domain-name-servers 10.0.0.5; option broadcast-address 10.0.3.255; option subnet-mask 255.255.252.0; option routers 10.0.0.1; allow client-updates; allow unknown-clients; max-lease-time 1814400; default-lease-time 604800; range 10.0.0.100 10.0.0.200; filename "/pxelinux.0"; next-server 10.0.0.5; } I configured it like this tutorial: Tutorial It doesn't worked for me, with the same error, because of this I copied the structure from a friend, it doesn't worked with the same error. But it works for him. Has anyone an idea, how to fix this problem? I don't know very well about syslinux and I would be happy if anyone can help me!

I want tp supersede the name server information, which I get from the DHCP server with my own configuration. Therefor I'm using the following option in my /etc/dhcp/dhclient.conf: supersede domain-name-servers 1.1.1.1, 2.2.2.2, 3.3.3.3; Everything works well, but I want to add IPv6 addresses as well as this is a dual stack server. The following statement does not work (I get /etc/dhcp/dhclient.conf line 56: semicolon expected. in the syslog): supersede domain-name-servers 1.1.1.1, 2.2.2.2, 3.3.3.3, ::1, 2000::BEEF, FURTHER_IPv6_ADDRESS; So my question is: How to I add IPv6 addresses to the supersede domain-name-servers option in /etc/dhcp/dhclient.conf?

I have a computer, C, a router, R, and a Raspberry Pi, P.  They are connected: Internet R P C Now I want C to be able to access the internet. The P has wlan0 and eth0, so my first thought was to bridge eth0 and wlan0, but that is not possible due to the nature of Wi-Fi, I've learned. The next approach is to add a DHCP server to P and let C lease an IP number.  It works fine; ip route on C gives: `10.254.239.0/27 dev eth0 src 10.254.239.13 default via 10.254.239.10 dev eth0 ` and ifconfig on P gives

eth0      Link encap:Ethernet  HWaddr b8:27:eb:44:bb:71  
          inet addr:10.254.239.10  Bcast:10.254.239.31  Mask:255.255.255.224
          inet6 addr: fe80::3206:e7e:fb7e:23d5/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:569 errors:0 dropped:0 overruns:0 frame:0
          TX packets:235 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:142936 (139.5 KiB)  TX bytes:50384 (49.2 KiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:19 errors:0 dropped:0 overruns:0 frame:0
          TX packets:19 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:1444 (1.4 KiB)  TX bytes:1444 (1.4 KiB)

wlan0     Link encap:Ethernet  HWaddr b8:27:eb:11:ee:24  
          inet addr:192.168.0.106  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::2501:6a8:8bcf:4a40/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:5415 errors:0 dropped:4989 overruns:0 frame:0
          TX packets:454 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:815495 (796.3 KiB)  TX bytes:49230 (48.0 KiB)

C can ping P but not R, leaving me to believe that P has some routing error. How can I configure P to pass traffic between R and C? ip route on P gives:

default via 192.168.0.1 dev wlan0  metric 303 
10.254.239.0/27 dev eth0  proto kernel  scope link  src 10.254.239.10 
192.168.0.0/24 dev wlan0  proto kernel  scope link  src 192.168.0.106  metric 303 

Also on P:

$ cat /proc/sys/net/ipv4/ip_forward
1

Running **ISC DHCP Server 4.4**. *(I know, I know, it's EOL...there was a very good reason I uninstalled **Kea-DHCP-Server** and decided to go with it's predecessor **ISC-DHCP-Server**...though I can't recall what it was right now...)* I appear to be getting leases, but the leases file is empty. I cannot work out where the leases are being tracked. dhcp-lease-list shows nothing. /var/lib/dhcp/dhcpd.leases only lists old leases and the file access time shows it hasn't been updated recently. tcpdump -vv -n -i eth0 'udp and port 67' shows DHCP traffic as expected. Scratching my head wondering what is going on.

I have a VM that is acting as a DC for a Windows VM, however, due to some shenanigans that systemd had been playing repeatedly (the boot process would hang inexplicably with the CPU load going straight through the roof, forcing me to kill the DC and restarting it, possibly multiple attempts required), I decided to switch to System V init, however, now I am experiencing a problem with the ISC DHCP server that I'm using to distribute IP addresses to the subnet the Windows VM is attaching to. The boot sequence is taking place normally until it reaches the start script of the DHCP server, however, in that moment the boot process locks up and refuses to continue. This, of course, causes anything later in the bootup sequence to not get executed, and even any ttys aren't brought up (not even the serial console that I have set up for the VM). Fortunately SSH is started before the DHCP server is launched so I can still SSH to the VM.\ When the server hangs, the following message is appearing:\ Launching IPv4 server only.\ However, the expected Starting ISC DHCPv4 server: dhcpd. doesn't even appear. Now, when doing a ps -ef | grep dhcp I get the following output:

root      1118     1  0 04:15 ?        00:00:00 dhclient -4 -v -i -pf /run/dhclient.enX0.pid -lf /var/lib/dhcp/dhclient.enX0.leases -I -df /var/lib/dhcp/dhclient6.enX0.leases enX0
root      1444  1272  0 04:15 ?        00:00:00 /bin/sh /etc/init.d/isc-dhcp-server start
root      1453  1444  0 04:15 ?        00:00:00 /usr/sbin/dhcpd -t -4 -q -cf /etc/dhcp/dhcpd.conf
ntp       1531     1  0 04:15 ?        00:00:00 /usr/sbin/ntpd -p /var/run/ntpd.pid -g -c /run/ntp.conf.dhcp -u 109:117
root      1712  1588  0 04:34 pts/0    00:00:00 grep dhcp

Next, when checking any ports opened by the dhcpd, I cannot find anything so I strongly suspect that the process hiccups during its attempt to open its UDP port. The network interface in question is a Xen PV interface attached to a bridge defined and set up in Domain-0.\ Within the DomU (the domain controller) this is the stanza from /etc/network/interfaces: allow-hotplug enX1 iface enX1 inet static address 192.168.128.1/24 The bridge to which the associated back-end is attached is defined as follows:

auto br1
iface br1 inet manual
      bridge_ports none
      bridge_stp on
      bridge_hello 10
      bridge_maxage 40
      bridge_bridgeprio 0
      bridge_fd 5

The question is, what is causing this hiccup, and how can it be resolved? Currently my only option is to kill the hanging DHCP server process to get the init script that is invoking it unstuck and so get the boot process to complete, but that is highly suboptimal at best, especially as it makes the SSH that I'm using to intervene unusable (no input possible) so I have to kill it in the process. This at least gets the boot process unstuck so that it can complete.\ Another interesting message that is showing up when killing the DHCP server (in the given example it would be kill -TERM 1453) is this one: dhcpd self-test failed. Please fix /etc/dhcp/dhcpd.conf. The error was: However, when starting it manually with service isc-dhcp-server start, everything works normally, and the server becomes fully operational without any further issues.

Using debian, and installed *isc-dhcp-server* via the following command sudo apt -y install isc-dhcp-server After agreeing to any dependencies, the follow error message was thrown Job for isc-dhcp-server.service failed because the control process exited with error code. See "systemctl status isc-dhcp-server.service" and "journalctl -xe" for details. Ive restarted my machine, and also tried to run the followng sudo service isc-dhcp-server start This just re-prints the same error message as above. The error asks to run **systemctl status isc-dhcp-server.service** which returns ● isc-dhcp-server.service - LSB: DHCP server Loaded: loaded (/etc/init.d/isc-dhcp-server; generated) Active: failed (Result: exit-code) since Mon 2024-03-11 00:33:46 GMT; 12min ago Docs: man:systemd-sysv-generator(8) Process: 2980 ExecStart=/etc/init.d/isc-dhcp-server start (code=exited, status=1/FAILURE) **sudo journalctl -u isc-dhcp-server.service** returns isc-dhcp-server: Launching IPv4 server only. dhcpd: /etc/dhcp/dhcpd.conf line 13: subnet 192.168.2.101 netmask 255.255.255.0: bad subnet number/mask combination. dhcpd: subnet 192.168.2.101 netmask 255.255.255.0 dhcpd: ^ dhcpd: Configuration file errors encountered -- exiting dhcpd: dhcpd: If you think you have received this message due to a bug rather dhcpd: than a configuration issue please read the section on submitting isc-dhcp-server: dhcpd self-test failed. Please fix /etc/dhcp/dhcpd.conf. isc-dhcp-server: The error was: dhcpd: bugs on either our web page at www.isc.org or in the README file dhcpd: before submitting a bug. These pages explain the proper dhcpd: process and the information we find helpful for debugging. dhcpd: exiting. dhcpd: Internet Systems Consortium DHCP Server 4.4.1 isc-dhcp-server: Internet Systems Consortium DHCP Server 4.4.1 isc-dhcp-server: Copyright 2004-2018 Internet Systems Consortium. isc-dhcp-server: All rights reserved. isc-dhcp-server: For info, please visit https://www.isc.org/software/dhcp/ dhcpd: Copyright 2004-2018 Internet Systems Consortium. dhcpd: All rights reserved. dhcpd: For info, please visit https://www.isc.org/software/dhcp/ dhcpd: /etc/dhcp/dhcpd.conf line 13: subnet 192.168.2.101 netmask 255.255.255.0: bad subnet number/mask combination. dhcpd: subnet 192.168.2.101 netmask 255.255.255.0 isc-dhcp-server: /etc/dhcp/dhcpd.conf line 13: subnet 192.168.2.101 netmask 255.255.255.0: bad subnet number/mask combination. isc-dhcp-server: subnet 192.168.2.101 netmask 255.255.255.0 isc-dhcp-server: ^ isc-dhcp-server: Configuration file errors encountered -- exiting MY MACHINE CONFIG FILES ----------------------- sudo nano /etc/dhcp/dhcpd.conf ... # option definitions common to all supported networks... option domain-name "example.org"; option domain-name-servers 8.8.8.8; ... subnet 192.168.2.101 netmask 255.255.255.0 { option routers pepper.spices.org; } ... authoritative; ... And sudo /etc/default/isc-dhcp-server ... DHCPDv4_CONF=/etc/dhcp/dhcpd.conf ... INTERFACESv4="eth0" ...

I am very new to kea-dhcp. I am trying to use kea-dhcp 2.0.1 version. below is my interface configuration mentioned in "dhcp.conf" "Dhcp4": { "interfaces-config": { "interfaces":[ "eth1", "eth2" ], "dhcp-socket-type" : "raw" }, When i try to start dhcp server it gives below error 058 ERROR [kea-dhcp4.dhcp4/37797.139924860343616] DHCP4_PARSER_FAIL failed to create or run parser for configuration element interfaces-config: Failed to select interface: interface 'eth1' doesn't exist in the system (/tmp/kea-dhcp.conf:1:49) (/tmp/kea-dhcp.conf:1:34) By the time i start dhcp server "eth1" did not get created, "eth2" interace is up and has valid IP but dhcp server failed to start since 1st interface mentioned in the "interface-config" is not created. How can i resolve this problem? Is there any option where dhcp server checks all interfaces mentiond and try to start and listen on interfaces which are created and UP?

I have VM which is working with "Host-Only Adapter". I disabled VirtualBox's built-in DHCP-server. I've installed isc-dhcp-server on my hypervisor. Then I added the subnet

subnet 10.10.54.0 netmask 255.255.255.0 {
  range 10.10.54.2 10.10.54.254;
  option routers 10.10.54.1;
  option domain-name-servers 8.8.8.8, 8.8.4.4;
  default-lease-time 600;
  max-lease-time 7200;
}

And added a fixed address for virtual machine.

host 10-10-54-11 {
  hardware ethernet 08:00:27:de:7e:cc;
  fixed-address 10.10.54.11;
}

My virtual machine has MAC-address 08:00:27:de:7e:cc. I'm trying to send a DHCP-request from my virtual machine by this command: nmap --script broadcast-dhcp-discover. However, when DHCPd receives a request for offering IP-address for VM, DHCPd shows a completely different MAC-address and doesn't send a fixed address

root@hypervisor:/etc/dhcp# systemctl status isc-dhcp-server
● 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 Mon 2023-11-13 12:28:09 +05; 9min ago
     Docs: man:dhcpd(8)
 Main PID: 12274 (dhcpd)
    Tasks: 1 (limit: 4915)
   CGroup: /system.slice/isc-dhcp-server.service
           └─12274 dhcpd -user dhcpd -group dhcpd -f -4 -pf /run/dhcp-server/dhcpd.pid -cf /etc/dhcp/dhcpd.conf

Nov 13 12:28:09 hypervisor dhcpd:    you want, please write a subnet declaration
Nov 13 12:28:09 hypervisor dhcpd:    in your dhcpd.conf file for the network segment
Nov 13 12:28:09 hypervisor dhcpd:    to which interface eth0 is attached. **
Nov 13 12:28:09 hypervisor dhcpd: 
Nov 13 12:28:09 hypervisor dhcpd: Sending on   Socket/fallback/fallback-net
Nov 13 12:28:09 hypervisor dhcpd: Server starting service.
Nov 13 12:28:14 hypervisor dhcpd: DHCPDISCOVER from de:ad:c0:de:ca:fe via vboxnet4
Nov 13 12:28:15 hypervisor dhcpd: DHCPOFFER on 10.10.54.3 to de:ad:c0:de:ca:fe via vboxnet4
Nov 13 12:32:39 hypervisor dhcpd: DHCPDISCOVER from de:ad:c0:de:ca:fe via vboxnet4
Nov 13 12:32:40 hypervisor dhcpd: DHCPOFFER on 10.10.54.3 to de:ad:c0:de:ca:fe via vboxnet4

Is it a bug? How to fix this problem?

I'm currently building a homebrew router, with some changes from my previous builds for more flexibility. I'm running an ubuntu server minimal base, network interfaces managed by netplan ,firewalld for firewall management and am trying to use kea for dhcp The hardware is a mini PC with 5 ports - 2 10 gig, and 3 2.5G. I've had it configured in netplan such that the 2 10 gig ports are named wan and lan, and the 3 2.5 gig pots named eth0-2 to match the physical labels on the hardware. My eventual intended goal is to set up kea to have lan, and ports eth0 and eth1 serving one subnet and eth2 serving a different subnet. I've tested that with static IPs on clients- setting the router side IP as the default gateway, this works, so I'm fairly certain my firewall rules are sound - I'd be happy to share any settings as needed. I've also gotten this working with a *single* interface, but I'd like to use more than one. In theory I could bridge them, but i want to get a single subnet working before trying to add a second one on another interface. For testing purposes, and to try to get a minimal viable product, I'm trying to get lan and eth0 working first. I've configured lan as 10.0.0.1 and eth0 as 10.0.0.2 I've shared minimal snippets of the kea-dhcp4 conf file below but the full version is here I've a few issues here. Firstly if I add more than one interface like so

"interfaces-config": {      
        "interfaces": [ "lan", "eth0" ]
          
        
    },

It serves only lan, and not eth0. In theory I could bridge them, but I want to serve a different range on eth2 later. It works if I only have eth0 OR lan but not both. It does seem a valid setup though since if I run sudo kea-dhcp4 -t /etc/kea/kea-dhcp4.conf I get

023-09-17 14:16:33.423 INFO  [kea-dhcp4.hosts/1824.139761470586496] HOSTS_BACKENDS_REGISTERED the following host backend types are available: mysql postgresql
2023-09-17 14:16:33.423 WARN  [kea-dhcp4.dhcpsrv/1824.139761470586496] DHCPSRV_MT_DISABLED_QUEUE_CONTROL disabling dhcp queue control when multi-threading is enabled.
2023-09-17 14:16:33.423 WARN  [kea-dhcp4.dhcp4/1824.139761470586496] DHCP4_RESERVATIONS_LOOKUP_FIRST_ENABLED Multi-threading is enabled and host reservations lookup is always performed first.
2023-09-17 14:16:33.423 INFO  [kea-dhcp4.dhcpsrv/1824.139761470586496] DHCPSRV_CFGMGR_ADD_IFACE listening on interface lan
2023-09-17 14:16:33.423 INFO  [kea-dhcp4.dhcpsrv/1824.139761470586496] DHCPSRV_CFGMGR_ADD_IFACE listening on interface eth0
2023-09-17 14:16:33.423 INFO  [kea-dhcp4.dhcpsrv/1824.139761470586496] DHCPSRV_CFGMGR_SOCKET_TYPE_DEFAULT "dhcp-socket-type" not specified , using default socket type raw
2023-09-17 14:16:33.423 INFO  [kea-dhcp4.dhcpsrv/1824.139761470586496] DHCPSRV_CFGMGR_NEW_SUBNET4 a new subnet has been added to configuration: 10.0.0.0/24 with params: t1=900, t2=1800, valid-lifetime=3600

The actual subnet settings are probably useful here to so I have shared them below

"subnet4": [
        {
            // Subnet identifier should be unique for each subnet.
            "id": 1,

            // This is mandatory parameter for each subnet.
            "subnet": "10.0.0.0/24",
            //testing explicit interfaces. Can't do more than 1
            //"interface": "eth0"

            "pools": [ { "pool": "10.0.0.51 - 10.0.0.200" } ],

            "option-data": [
                {
                    "name": "routers",
                    "data": "10.0.0.1, 10.0.0.2"
                }
            ],

            "reservations": [

                {
                    "hw-address": "xx:xx:xx:xx:xx:xx",
                    "ip-address": "10.0.0.50"
                }

                
            ]
            
    ],

Unfortunately my test client system's running windows - but from what I can tell, Its giving out only the first default gateway, and I suspect that's breaking routing. Is there any way I can use one or more interfaces with the same subnet?

I was thinking I'd rather not assign my TV a default gateway, and since I use ISC DHCP 4.4 I tried to override the general subnet configuration with a host specific configuration, like this:

host Samsung-TV {
        hardware ethernet aa:bb:cc:dd:ee:ff;
        option routers;
}

Not too surprisingly this was a configuration error. The below config works, but is technically assigning a gateway:

host Samsung-TV {
        hardware ethernet aa:bb:cc:dd:ee:ff;
        option routers 0.0.0.0;
}

Is there any way to override option routers with the actual *absence* of that option? Or is that a useless technicality that shouldn't matter?

Just like how dhclient captures dhcp response and stores it in env, is there a way to capture information like option 43 from systemd-networkd's DHCP client and store it in env ? I have proxy URL stored in option 43 and I need to access that information. tcpdump shows response has vendor 43 data, but I am unable to extract it via scripts or from env. Is there any way ?

Before launching a VM from my script, I need to figure out which IP address it will get. So I did: dhclient And this works, because dhclient uses the MAC address from the macvtap interface specified, and returns me the IP address from the DHCP server. This is not a foolproof solution, because there may be some people who have a router at home that does not always return the same IP for the same MAC. But every router I ever owned did, so if it works for 99 percent of the cases it's good enough for me. But the problem is that dhclient also makes changes to the local configuration because it thinks I want to actually use that address on the host. There is a -n flag that should prevent this, but it is not supported by Debian or most other distributions. So what is the best way to just ask a DHCP server which IP it is planning to serve to a certain MAC address, without actually modifying any settings on the host?

I want to reserve and get assigned an pre-defined IP address for wlan0 interface on my client. I have set: # cat /etc/NetworkManager/conf.d/dhcp-client.conf:

[main]
dhcp=dhclient

# cat /etc/dhcp/dhclient.conf:

# Configuration file for /sbin/dhclient.
#
# This is a sample configuration file for dhclient. See dhclient.conf's
#	man page for more information about the syntax of this file
#	and a more comprehensive list of the parameters understood by
#	dhclient.
#
# Normally, if the DHCP server provides reasonable information and does
#	not leave anything out (like the domain name, for example), then
#	few changes must be made to this file, if any.
#

option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;

send host-name = gethostname();
request subnet-mask, broadcast-address, time-offset, routers,
	domain-name, domain-name-servers, domain-search, host-name,
	dhcp6.name-servers, dhcp6.domain-search, dhcp6.fqdn, dhcp6.sntp-servers,
	netbios-name-servers, netbios-scope, interface-mtu,
	rfc3442-classless-static-routes, ntp-servers;

#send dhcp-client-identifier 192.168.0.108;
#send dhcp-lease-time 3600;
#supersede domain-name "fugue.com home.vix.com";
#prepend domain-name-servers 127.0.0.1;
#require subnet-mask, domain-name-servers;
#timeout 60;
#retry 60;
#reboot 10;
#select-timeout 5;
#initial-interval 2;
#script "/sbin/dhclient-script";
#media "-link0 -link1 -link2", "link0 link1";
#reject 192.33.137.209;

#alias {
#  interface "eth0";
#  fixed-address 192.5.5.213;
#  option subnet-mask 255.255.255.255;
#}

#lease {
#  interface "wlan0";
#  fixed-address 192.168.0.108;
#  medium "link0 link1";
#  option host-name "banan.dev";
#  option subnet-mask 255.255.255.0;
#  option broadcast-address 192.33.137.255;
#  option routers 192.168.0.1;
#  option domain-name-servers 127.0.0.1;
#  renew 2 2000/1/12 00:00:01;
#  rebind 2 2000/1/12 00:00:01;
#  expire 2 2000/1/12 00:00:01;
#}

host bananapim2zero {
    hardware ethernet ac:6a:a3:27:8a:e1;
    fixed-address 192.168.0.108;
}

# systemctl status NetworkManager.service

NetworkManager.service - Network Manager
     Loaded: loaded (/lib/systemd/system/NetworkManager.service; enabled; vendor preset: enabled)
     Active: active (running) since Wed 2023-04-19 20:45:08 CEST; 6min ago
       Docs: man:NetworkManager(8)
   Main PID: 1103 (NetworkManager)
      Tasks: 7 (limit: 888)
     Memory: 11.5M
        CPU: 1.274s
     CGroup: /system.slice/NetworkManager.service
             ├─1103 /usr/sbin/NetworkManager --no-daemon
             └─1303 /sbin/dhclient -d -q -sf /usr/lib/NetworkManager/nm-dhcp-helper -pf /run/NetworkManager/dhclient-wlan0.pid -lf /var/lib/NetworkManager/dhclient-56269e02-ee63-423f-bc6c-97067633aa9a-wlan0.lease -cf /var/lib/NetworkManager/dhclient-wlan0.conf wlan0

Apr 19 20:45:17 bananapim2zero NetworkManager:   [1681929917.5831] policy: set 'jebnato' (wlan0) as default for IPv4 routing and DNS
Apr 19 20:45:18 bananapim2zero NetworkManager:   [1681929918.2894] device (wlan0): Activation: successful, device activated.
Apr 19 20:45:18 bananapim2zero NetworkManager:   [1681929918.2982] manager: NetworkManager state is now CONNECTED_GLOBAL
Apr 19 20:45:18 bananapim2zero NetworkManager:   [1681929918.3126] manager: startup complete
Apr 19 20:45:18 bananapim2zero NetworkManager:   [1681929918.3193] device (wlan0): ipv6: duplicate address check failed for the fe80::1ea1:1ea:1b97:6dbd/64 lft forever pref forever lifetime 11-0[4294967295,4294967295] dev 2 flags permanent,noprefixroute,tentative,0x8 s>
Apr 19 20:45:18 bananapim2zero NetworkManager:   [1681929918.3196] device (wlan0): ipv6: duplicate address check failed for the fe80::f49e:9be3:cea2:c5c4/64 lft forever pref forever lifetime 11-0[4294967295,4294967295] dev 2 flags permanent,noprefixroute,tentative,0x8 >
Apr 19 20:45:18 bananapim2zero NetworkManager:   [1681929918.6471] device (wlan0): ipv6: duplicate address check failed for the fe80::1ea1:1ea:1b97:6dbd/64 lft forever pref forever lifetime 11-0[4294967295,4294967295] dev 2 flags permanent,noprefixroute,tentative,0x8 s>
Apr 19 20:45:19 bananapim2zero NetworkManager:   [1681929919.0517] device (wlan0): ipv6: duplicate address check failed for the fe80::f49e:9be3:cea2:c5c4/64 lft forever pref forever lifetime 12-0[4294967295,4294967295] dev 2 flags permanent,noprefixroute,tentative,0x8 >
Apr 19 20:45:19 bananapim2zero NetworkManager:   [1681929919.2169] device (wlan0): ipv6: duplicate address check failed for the fe80::2b24:4b8f:cfa4:39fe/64 lft forever pref forever lifetime 12-0[4294967295,4294967295] dev 2 flags permanent,noprefixroute,tentative,0x8 >
Apr 19 20:45:19 bananapim2zero NetworkManager:   [1681929919.2172] device (wlan0): linklocal6: failed to generate an address: Too many DAD collisions

/var/lib/NetworkManager/dhclient-wlan0.conf:

# Created by NetworkManager
# Merged from /etc/dhcp/dhclient.conf

# Configuration file for /sbin/dhclient.
#
# This is a sample configuration file for dhclient. See dhclient.conf's
#	man page for more information about the syntax of this file
#	and a more comprehensive list of the parameters understood by
#	dhclient.
#
# Normally, if the DHCP server provides reasonable information and does
#	not leave anything out (like the domain name, for example), then
#	few changes must be made to this file, if any.
#
option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;
#send dhcp-client-identifier 192.168.0.108;
#send dhcp-lease-time 3600;
#supersede domain-name "fugue.com home.vix.com";
#prepend domain-name-servers 127.0.0.1;
#require subnet-mask, domain-name-servers;
#timeout 60;
#retry 60;
#reboot 10;
#select-timeout 5;
#initial-interval 2;
#script "/sbin/dhclient-script";
#media "-link0 -link1 -link2", "link0 link1";
#reject 192.33.137.209;
#alias {
#  interface "eth0";
#  fixed-address 192.5.5.213;
#  option subnet-mask 255.255.255.255;
#}
#lease {
#  interface "wlan0";
#  fixed-address 192.168.0.108;
#  medium "link0 link1";
#  option host-name "banan.dev";
#  option subnet-mask 255.255.255.0;
#  option broadcast-address 192.33.137.255;
#  option routers 192.168.0.1;
#  option domain-name-servers 127.0.0.1;
#  renew 2 2000/1/12 00:00:01;
#  rebind 2 2000/1/12 00:00:01;
#  expire 2 2000/1/12 00:00:01;
#}
host bananapim2zero {
hardware ethernet ac:6a:a3:27:8a:e1;
fixed-address 192.168.0.108;
}
send host-name "bananapim2zero"; # added by NetworkManager

option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;
option ms-classless-static-routes code 249 = array of unsigned integer 8;
option wpad code 252 = string;

request; # override dhclient defaults
also request subnet-mask;
also request broadcast-address;
also request time-offset;
also request routers;
also request domain-name;
also request domain-name-servers;
also request domain-search;
also request host-name;
also request dhcp6.name-servers;
also request dhcp6.domain-search;
also request dhcp6.fqdn;
also request dhcp6.sntp-servers;
also request netbios-name-servers;
also request netbios-scope;
also request interface-mtu;
also request rfc3442-classless-static-routes;
also request ntp-servers;
also request ms-classless-static-routes;
also request static-routes;
also request wpad;
also request root-path;

that means NetworkManager should use dhclient as it's DHCP backend and I have added to it's configuration the section (probably wrong one) to fix (but I want reserve so it won't fail if not available) the address. not working; badly documented. OS: armbian latest thanks in advance

I am trying to figure out the max number of leases I can define in dhcpd.leases file for the DHCP server. Does anyone know how many max can it support? Thanks

I want to add a static route to 10.13.0.1/32 via 192.168.178.10 to my dhcpd.conf of my dhcpd server. Unfortunately this seems to be insanely complicated. I tried the following: option static-routes 10.13.0.1 192.168.178.10; However this will add a route to 10.0.0.0/8 via 192.168.178.10 which is undesired. I also tried: option rfc3442-classless-static-routes code 121 = array of unsigned integer 8; option ms-classless-static-routes 32, 10, 13, 0, 1, 192, 168, 178, 10; Which results in the dhcpd to no longer start: Feb 13 20:49:30 csh-gw dhcpd: For info, please visit https://www.isc.org/software/dhcp/ Feb 13 20:49:30 csh-gw dhcpd: /var/lib/dhcp//etc/dhcpd.conf line 63: unknown option dhcp.ms-classless-static-routes Feb 13 20:49:30 csh-gw dhcpd: option ms-classless-static-routes 32, Feb 13 20:49:30 csh-gw dhcpd: ^ Feb 13 20:49:30 csh-gw dhcpd: Starting ISC DHCPv4 Server Feb 13 20:49:30 csh-gw dhcpd: please see /var/log/rc.dhcpd.log for details ..failed Googling for this issue did only yield results of adding routes to entire networks including a default gateway, which I do not want.