Apparently the isc-dhcp-server is started too early in the boot sequence, it states that it has nothing to do. If I just log directly in as root and start it using the init.d-script, it starts normally.  My setup is basically an utterly standard router, with an eth0 on the inet side, and an eth1 on the lan side. However, I've defined a bridge instead of the eth1 for the lan-side. Thus, the lan-part of the network isn't up until the bridge is up.  I currently believe that the dhcp server is brought up before the bridge is brought up, probably because the bridge is brought up with the 'networking' task, while the eth's are taken up with the 'network-interface' tasks - which are run earlier. (also, the bridge takes a small age to get up compared to the eth's).  If I do take away the bridge config, instead using eth1 directly for the lan side, things work. (However, judging by syslog, things are still tight.)  Ideas of how the get DHCP to start later?  (The reason for the bridge, is to be able to use KVM with bridged networking..)
123384
I have Ubuntu 10.04 server currently setup with dhcp3-server as well as a bridged interface (br0) for use with virtual machines. The problem I have is that when the server reboots, dhcp3-server fails to load because of the extra delay caused by bringing up the bridged interface.  Essentially br0 doesn't have an IP address for use with DHCP3-Server until late in the boot cycle, well after DHCP3-server has attempted to load.  Once the server has booted I can run '/etc/init.d/dhcp3-server start' without any issue.  Is there any way I can either: - Force dhcp3-server to wait until the interface has loaded before attempting to load? - Start dhcp3-server after everything else has loaded up?
68959
We can use multiple IP addresses for a single interface in Linux (eg. eth0:0, eth0:1). But can we use DHCP and static IP at the same time? eth0:1 should have a static IP address and eth0:0 should be configured using DHCP.  How can we accomplish both?
52819
I want to use certain DNS servers regardless of whatever I get through DHCP. I'm trying to configure dhclient to ignore those, but I can't seem to get it to work.  Per advice from  I added supersede domain-name-servers 8.8.8.8, 8.8.4.4; stanza to my /etc/dhcp/dhclient.conf file. I also tried  and removed domain-name-servers and domain-search values from request directive. Both of those, applied separately as well as together, seem to have no effect. After running sudo dhclient -r and then sudo dhclient, I still find following entries in /etc/resolvconf/run/interfaces/enp2s0.dhclient:  domain lan nameserver 192.168.1.1   which prompt resolvconf to put nameserver 192.168.1.1 in my /etc/resolv.conf file.  I double-checked if I don't miss any semicolons or similar syntax elements. How can I get my configuration to work? I don't want to remove resolvconf, since it manages changes in my nameservers when I use corporate VPN and it does it well. It looks like dhclient is the offending party here.  Here's my current /etc/dhcp/dhclient.conf with default comments removed for the sake of clarity:  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, 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;  #supersede domain-name-servers 8.8.8.8, 8.8.4.4;   Update: per request in comment, here's output of ps ax | grep dhcp:  23528 pts/2    S+     0:00 grep dhcp
106677
I'm trying to set up a static IP address for my LTSP server as to configure one of my two NICs (internal one : Server -> Light client) via the /etc/network/interfaces , but when I open the interfaces file all I can see is this :  auto lo iface lo inet loopback   Is this normal?
123706
I am wondering if there is anything (software or hardware) out there that can do something I think I may have made up, Dynamic Static IPs. The idea is that when a new device connects to the local network this device/software acts as a DHCP server, if the device is new then it dynamically assigns it a new address that has never been used before and stores this MAC Address IP Address combination in a database, if the device's MAC is in the database the devices gets the same IP as before.  I am aware this is similar to sticky IP allocation but I don't want the IPs to stick for a while I want them to be superglued on for ever.  Bonus question: Is this possible using a Raspberry Pi running Raspbian on a network with around 100 devices? The RPi is already acting as the DHCP server and the router has this capability but it is turned off.  Many thanks in advance for any and all help offered!
11928
When I am online, I get following error and the tool does not start:  [root@dhcppc9 lin64]# ./ise No protocol specified _pn: cannot connect to X server :0.0   But everything is OK when I am not a superuser. Why that?  Edit  [root@dhcppc9 lin64]# export $(dbus-launch) No protocol specified   any suggestion?  Also   [root@dhcppc9 lin64]# xhost [+] No protocol specified xhost:  unable to open display ":0.0"
89812
I am wondering what is the difference between:  # ifconfig eth0:0 1.1.1.1/24   and just  # ip addr add 1.1.1.1/24 dev eth0   Btw I cannot do  # ip addr add 1.1.1.1/24 dev eth0:0 RTNETLINK answers: File exists   In ip addr show it appears differently :  eth0: &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast state UP qlen 1000  link/ether 8c:ae:4c:fe:1f:75 brd ff:ff:ff:ff:ff:ff inet 1.1.1.1/24 brd 1.1.1.255 scope global eth0:0 ---&gt; with ifconfig inet 2.2.2.2/24 scope global eth0 ----&gt; with ip   When should I prefer the first way and when should I prefer the second way? It seems more cool to
43509
I am a new with Linux, having years experience with Windows servers/desktops and am having issues setting a static IP. I am using a method used for previous versions of Ubuntu, which doesn't seem to work with 16.04  I have used the command sudo nano /etc/network/interface and added the following  iface enp0s25 inet static address 10.10.8.2 netmask 255.255.0.0 gateway 10.10.1.1 dns-nameservers 8.8.8.8 8.8.4.4   I have rebooted the system and the Ethernet is pretty much dead, ping doesn't work at all. I have tried to modify /etc/NetworkManager/NetworkManager.conf and made the following changes  #dns=dnsmasq (comment out the dnsmasq) [ifupdown] managed=true (changed from false)   With this I can get Ethernet to work sporadically, however it eventually fails.  I have tried this configuration on two other machines plus a virtual machine as well and all have the same results. I can confirm these settings work fine when I install Windows on any of these machines. As well when I let DHCP auto configure, everything works fine no issues.  I figure I am missing something here, setting up a static IP should not be difficult at all.
108719
Ubuntu 18.04 server on my home network I'm running:     dnsmasq for DHCP and DNS nginx as a reverse proxy to some web applications (running on localhost and on other hosts)   The nginx reverse proxy config uses hostnames, eg:  location / {         proxy_pass http://nas.mydomain.com:8080;   However, when rebooting the server, nginx tries to start up but fails due to not being able to resolve the hostnames in its config. If I start nginx up manually after boot, it starts up without error.  This leads me to believe that nginx is starting before dnsmasq is available to resolve the hostnames.  Is there a way to force nginx to start after dnsmasq?
49889
Connecting to the wireless is relatively simple.  After some struggle, you have wifi in your installer. You can install Ubuntu Server and everything is alright. You are ready to boot your new system.    After setup finished, wifi settings disappeared.  tl;dr: How do I connect to a wireless (WPA2 Personal) network from Ubuntu Server 12.10?    What I have tried so far:  Connected with iw* commands. Obtained IP address with dhclient. Put these commands to etc/rc.local.  On boot, the server waits 120 seconds with message "Waiting for network to come up"  To fix this, I removed everything /etc/network/interfaces (wpa-psk and wpa-ssid). This did not work. It was still waiting. I found an answer, which said I could just remove the /etc/... (the file that was in charge of the 120 second wait time.)    I did that, and kept a backup of it. Now the server waits ~3 seconds (modified sleep within the file) and boots up. However, there's no network connection available. It's some dhcp error.  As I was out of options, I tried using the one in comment. The one that used "tee". Turns out it does not work either.    How can this whole thing be so inconsistent? How can they not install the firmwares on the ISO while it would perfectly fit (673+~10MB = 683). How can the installer NOT copy the necessary files and set up the connection to be used later? (Or ask if the user wants to use it.)
58345
As we all know, to configure the network, we can edit /etc/network/interfaces and execute /etc/init.d/networking restart.  Today I try to use Ubuntu 17.10 and I've found the network configuration had changed. Now we should edit /etc/netplan01-netcfg.yaml and execute netplan apply.  OK, this might be a bad question but I really want to know why Ubuntu did such a change. Is there a strong reason to explain all of changes like this one?
25757
I'm trying to set up an OpenVPN server on my VPS for myself when I'm in public places, using this tutorial,   However whenever I try to start the server, it gives me this,  root@vps:~# /etc/init.d/openvpn start  * Starting virtual private network daemon(s)...                                                                 *   Autostarting VPN 'server'                                                                           [fail]   The log contains this  Tue Dec 11 10:53:32 2012 Diffie-Hellman initialized with 1024 bit key Tue Dec 11 10:53:32 2012 /usr/bin/openssl-vulnkey -q -b 1024 -m &lt;modulus omitted&gt; Tue Dec 11 10:53:33 2012 TLS-Auth MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ] Tue Dec 11 10:53:33 2012 ROUTE: default_gateway=UNDEF Tue Dec 11 10:53:33 2012 Note: Cannot open TUN/TAP dev /dev/net/tun: No such file or directory (errno=2) Tue Dec 11 10:53:33 2012 Note: Attempting fallback to kernel 2.2 TUN/TAP interface Tue Dec 11 10:53:33 2012 Cannot allocate TUN/TAP dev dynamically Tue Dec 11 10:53:33 2012 Exiting   So obviously it's something to do with the tun, but I don't understand how to fix it.  Thanks!
21745
When running isc-dhcp the leases file seems to grow indefinitely (several hundred MB). If I restart the isc-dhcp service, the file shrinks to 1.5MB.   How can I have isc-dhcp flush expired records periodically without restarting the full service?
115097
Cause Ubuntu uses Upstart instead of init, there is some different from Red Hat. But How can I get the list of each runlevel number standing for, such as init 0 means shutdown. man init can't show the list. So which command or man page cant print the list. Thx!
40597
Is there a simple ping-like command to test whether a DHCP service is running on a network? ...on Linux
29167
Is there a workaround for ?  Problem: I want to have a network configuration on Debian with the following properties:   Automatically ifup network interface when a cable is plugged in boots without blocking for a long time when no cable is connected on boot not switching my init system   The standard way to do this would be the following snippet in /etc/network/interfaces:  allow-hotplug eth0 iface eth0 inet dhcp   However, this leads to the problem described in the linked bug report: The boot process blocks for >1min when no network cable is plugged in with the following message:  configuring network interfaces... ifup: waiting for lock on /run/network/ifstate.eth0   A workaround given in  seems to be changing allow-hotplug to auto:  auto eth0 iface eth0 inet dhcp   This effectively makes the boot blocking message disappear, however, the system now blocks right before a login prompt is shown at tty1. This time dhclient is blocking because it tries to get a dhcp reply on eth0, which is not connected, and waits for several attempts to timeout. The login prompt only appears after the dhclient timeouts.  For users with a graphical DE, this might not be a problem, as they don't need to log in on tty1, instead their DE boots and they never see the dhclient message.  Another workaround would probably be to use network-manager. Ideally, I would prefer to not use networkmanager, but as a last resort, I tried that. However, on Debian buster, network-manager's dependency chain conflicts with sysvinit-core, which is my init system.  The last alternative which comes to my mind is to not configure eth0 in interfaces(5). This makes all boot blocks go away, however, I need to manually ifup eth0 after plugging in an ethernet cable.  Any better ideas?  UPDATE: To address the quote from @sourcejedi, "allow-hotplug" is specified to "start interface  when the kernel detects a hotplug event from the interface" in the Debian docs under . Related questions:  and
14901
I just switched to debian jessie, and most things run okay, including my graphical display manager wdm.  The thing is, I just don't understand how this works. Obviously my /etc/init.d/wdm script is called, because when I put an early exit in there, wdm is not started. But when I alternatively rename the  /etc/rc3.d directory (my default runlevel used to be 3), then wdm is still started.  I could not find out how systemd finds this script and I do not understand what it does to all the other init.d scripts.   When and how does systemd run init.d scrips? In the long run, should I get rid of all init.d scripts?