Networking :: Display DNS & DGW Provided By DHCP Server ?
May 4, 2011
If I use static TCP configuration, (my Linux is Red Hat, but SuSE is quite similar) I define DNS's in file "/etc/resolv.conf" and Default GateWay in file
"/etc/sysconfig/network" (/etc/sysconfig/network/routes undef SuSE).
So, when I want to display those values, I just display the contents of the file. But, if my TCP configuration uses DHCP server ... I dont know the command to display those values. PD.- in straight : I need a command to display the DNS's in effect on a TCP/IP configuration that uses a DHCP server. Also, a command to display Default Gateway would be welcome.
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May 31, 2010
I have a network consisting mostly of Windows Vista and 7 clients and an Ubuntu server. The server provides both the DHCP and NTP services through dhcp3-server and openntpd. In my dhcpd.conf, the subnet is declared as follows:
subnet 10.10.10.0 netmask 255.255.255.0 {
range 10.10.10.10 10.10.10.200;
option broadcast-address 10.10.10.255;
option routers 10.10.10.1;
option ntp-servers 10.10.10.1;
The clients don't seem to be using the NTP server though. When I capture the network traffic with Wireshark during the DHCP process, I also see no mention of the NTP option in the DHCP offer message. I am not quite sure if the clients would have to specifically request that option to receive it or if I have to make another configuration to offer the option.
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Oct 22, 2010
Back in April I set up a Ubuntu DHCP server and a multiple VLAN network [URL] to migrate our various servers, workstations, etc off the 192.168.1.1 /24 network that everything was on because we where running out of address space. I built out the new network and everything worked great except our AD server would never get an IP address from the DHCP server (static reservation) and even if I set the IP statically on the AD server it couldn't ping the gateway and noone could log in. After several attempts to resolve this, including bringing in outside help, we where never able to figure out what the problem was.
Now 6 months later I have time to revisit the issue without effecting the live network. I used Acronis and imaged the AD server last Friday, cloned it on to another box with the same hardware, and put it up on the new network that's been sitting unused for the last 6 months. Today when I statically set the IP on the AD server (which is what I want) it connects and I can ping it's gateway 192.168.1.1 and all the way across vlans to a test sales agent workstation at 192.168.8.xxx on vlan 800 but only if I statically assign the agents station an IP address. When I try to get an IP address via DHCP it fails as destination unreachable. Nothing has changed in the last 6 months on the DHCP server but now it for some reason can't ping its default gateway 192.168.1.1. All of the config files are the same as they where left from the post linked above aside from the vlan id's used where changed from 1's to 100's (i.e. vlan 3 is now vlan 300) /etc/network/interfaces
Code:
auto lo
iface lo inet loopback
auto vlan100
iface vlan100 inet static
[code]....
why it can't reach the gateway, when I do a tcpdump I can see the DHCP requests come in on eth0 but the server never responds and I'm pretty sure its because it isn't "seeing" them since it thinks there isn't a network connection but I don't know how to trouble shoot to find out where the problem lies.
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Jul 1, 2010
Back in April I set up a Ubuntu DHCP server and a multiple VLAN network [URL] to migrate our various servers, workstations, etc off the 192.168.1.1 /24 network that everything was on because we where running out of address space. I built out the new network and everything worked great except our AD server would never get an IP address from the DHCP server (static reservation) and even if I set the IP statically on the AD server it couldn't ping the gateway and noone could log in. After several attempts to resolve this, including bringing in outside help, we where never able to figure out what the problem was.
Now 6 months later I have time to revisit the issue without effecting the live network. I used Acronis and imaged the AD server last Friday, cloned it on to another box with the same hardware, and put it up on the new network that's been sitting unused for the last 6 months. Today when I statically set the IP on the AD server (which is what I want) it connects and I can ping it's gateway 192.168.1.1 and all the way across vlans to a test sales agent workstation at 192.168.8.xxx on vlan 800 but only if I statically assign the agents station an IP address.
When I try to get an IP address via DHCP it fails as destination unreachable. Nothing has changed in the last 6 months on the DHCP server but now it for some reason can't ping its default gateway 192.168.1.1. All of the config files are the same as they where left from the post linked above aside from the vlan id's used where changed from 1's to 100's (i.e. vlan 3 is now vlan 300) /etc/network/interfaces
Code:
auto lo
iface lo inet loopback
auto vlan100
[code]....
why it can't reach the gateway, when I do a tcpdump I can see the DHCP requests come in on eth0 but the server never responds and I'm pretty sure its because it isn't "seeing" them since it thinks there isn't a network connection but I don't know how to trouble shoot to find out where the problem lies.
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Mar 25, 2010
I am puzzled with trying to configure a linux (openSUSE) client to dhcp to eBox DHCP server. I am using dhclient to lease an IP address with dhclient eth0 -s 10.45.48.108 and get a response
openSUSE11232CL1 dhclient: DHCPDISCOVER on eth0 to 10.45.48.108 port 67 interval 4
openSUSE11232CL1 dhclient: DHCPOFFER from 10.45.48.108
openSUSE11232CL1 dhclient: DHCPREQUEST on eth0 to 10.45.48.108 port 67
openSUSE11232CL1 dhclient: send_packet: Network is unreachable
openSUSE11232CL1 dhclient: send_packet: please consult README file regarding broadcast address.
The server reports eBox141 dhcpd: DHCPDISCOVER from 00:0c:29:3e:57:a3 (openSUSE11232CL1.domain.net) via eth0
eBox141 dhcpd: DHCPOFFER on 10.45.200.2 to 00:0c:29:3e:57:a3 (openSUSE11232CL1.domain.net) via eth0
I interpret this as the server receives the request and the client accepting it but the lease does not last long and the connection breaks. what this could be and why the connection breaks? Or my undestanding is totally wrong on how it works and should work? And BTW, where is that README file that's referenced in the message I receive on the client?
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Mar 8, 2010
Currently I have my eth0 interface getting a DHCP address but at times the DHCP server will not be reachable. Sooo what I would like my server to do is if it cannot find a DHCP server assign a static address to eth0. Then start the DHCP service so it can then dish out some addresses.How can I do this? Surely it is possible
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May 21, 2010
How do we configure to resolve for hostnames when an IP address is provided to the DNS server.
Things I tried
The DNS daemon was started by the resolution failed. Find the logs below
** server can't find 11.127.168.192.in-addr.arpa: NXDOMAIN
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May 27, 2010
On a remote system, when all you have is the ssh CLI -
How do you find out the ip addresses for:the Gateway
the DHCP server
the DNS server
Don't need to make any changes.
Which commands will display this info?
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Aug 4, 2010
I have an embedded device for which I've created an html configuration page. This page allows you to set static IPs, dhcp, and can scan for wireless devices.My problem is that in order to access the device it requires that it runs as a dhcp server otherwise people are not assigned an IP and so can not access the embedded devices static IP. (This config page is for the laymen and so they are not the type who are able to set up their own static IPs). One of the potential options is to have the device connect to the network on eth0 acting as a dhcp client. However this prevents me from running a dhcp server.One solution I can think of is running a dhcp server only if it doesn't detect another dhcp server running on the network.
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Apr 26, 2010
when i assign ip manually to a machine it gets ping by server and it also itself pings server but when i chose to use client machine as dhcp , so that it can directly get assigned ip from server, it does not get ip, instead random ip is provided which is out of range specified at server side in /etc/dhcpd.conf file.
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Mar 17, 2010
I'm trying to build a linux(fedora 12) dhcpd server(and gateway), that have 3 network cards(eth0 have with public ip, eth1 192.168.2.1 class and eth3 with 192.168.3.1 class).
Because I have just a switch, I want to put both cables(from eth1, eth2) in the switch. Every client has 2 network card(eth0, eth1). My question is, is there any way to conf eth0 to take from server ip from 192.168.2.1 class, and eth1 from 192.168.3.1? The internet will work only on eth0.
my dhcpd.conf for now looks like this:
subnet 192.168.2.0 netmask 255.255.255.0 {
option subnet-mask 255.255.255.0;
option routers 192.168.2.1;
[Code]....
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Sep 16, 2010
I have two servers behind different networks. First network is protected with firewall provided by the router and there is no firewall in the server:
[Code]....
As you see, there are no difference in nmap output If I check with tcpdump, which packets are sent from 192.168.217.73 and 192.168.13.19(tcpdump -i eth0 src host 192.168.217.73 and tcpdump -i eth0 src host 192.168.13.19 respectively) towards me during nmap scan, there are none. It's understandable, as there should be no reply when port is filtered. Is there somehow possible to detect, whether firewall is active in the server or in the router?
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Feb 22, 2010
Is this possible to record keyboard inputs in a file which will be provided during running a script.? Means suppose there is a script ./instal.sh To run this script, some inputs need to be provided.Is this possible to record these inputs in a file?
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Jun 19, 2011
We have a network of 20 boxes and the router dealt with DHCP, but I'm planning to assign the DHCP task to the linux box. Any heads up? eth card configuration, network topology... etc.?
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Aug 17, 2010
I have 2 Ethernet connections, one (eth0) for the internet which gets set with dhcp, and one (eth1) for my internal network on which I have dhcp3-server running. I set eth1 to use static IP in interfaces, but every time I reset the network, it is fine for a couple of minutes, and switches over do being served by my own dhcp server on the same machine. (the interfaces file clearly says "iface eth1 inet static")
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Dec 13, 2010
I reinstalled Ubuntu server, now, as always I have to start off with 8.04 then upgrade to 10.04, and I've never had a problem with this before on this machine or any other for that matter. The problem is, this time I have installed and Ubuntu installer cannot see a DHCP, I go a head and install anyway and fire up Ubuntu and there is no internet access, I have two network cards plugged in, when I type in ifconfig it shows only lo and no network cards, and yet when I check lspci ot shows both network cards are there and when either are plugger in it shows connection on both the connector at the stack end and on the router.
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May 6, 2011
i have a homework where i have to set up a dhcp server on linux. I am using ubuntu. I tried following: [URL] However after running "sudo apt-get install dhcp3-server" the file "/etc/default/dhcp3-server" does not appear.
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Jan 24, 2010
This is probably an odd request, but figured I'd ask in case someone knew. We have a lab that has the IP range 172.10.0.0/16 (255.255.0.0). The lab gateway/DHCP assigns an IP in the range of 172.10.0.2-172.10.0.254. I want to set up my own DHCP server on a specific range, for example 172.10.10.1-172.10.10.254. I create a new host fine, but since it's set for DHCP, it uses the DHCP server at 172.10.0.1. Is there a way to force it to use a different DHCP server on the client side? I realize that I can work around this with exclusions on the 172.10.0.1 DHCP server, or use iptables to deny DHCP requests to specific MACs, but wanted to know if there was an (easier?) way to configure the client to use the 172.10.10.1 DHCP server instead of the 172.10.0.1 server?
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Apr 1, 2010
I have a scenario where a Debian (in this case) device will be connected to an existing LAN.What I then want said box to do, is to query the LAN to see if there is an existing DHCP server present. If there isn't one - then simply use the Debian box as the DHCP server (which works fine atm).If there is an existing one - I need the Debian box to be able to turn off it's own internal one and get it's details from the existing server (ie. change from server to client).
These action will need to be sat in the background as well - just in case another DHCP server appears on the LAN after this box does. Don't shoot me for saying it - but I know Windoze server does this. Is there a 'script/util' that anyone knows of (I am trying to do this auto-magically)?
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Jan 15, 2010
On my network drive web control panel I have got such an option:What would a dhcp server do on a network hard disk?
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Dec 7, 2010
I got a machine with RedHat Enterprise Linux 5 installed. I set the ifcfg-eth0 as following:
Code:
DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes
TYPE=Ethernet
when the machine rebooted, eth0 has the ip address 192.168.24.234. But if executing 'dhclient', eth0 will get the ip address 10.200.34.208, which is my expected ip address. I'm not quite familiar with networking things. I don't know what's going on there. Why should I need to execute 'dhclient' to obtain the expected ip address? Is there any way to obtain the ip address 10.200.34.208 right after host boot?
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Feb 9, 2010
how to configure DHCP server on centos linux and how to configure FTP server on centos linux
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Jul 20, 2011
How to set up DHCP server in Redhat Linux 6
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May 7, 2010
I have installed Centos 5 on a virtual machine (esx4i). I set it to obtain an IP address from the DHCP sever, which is a broadband router, it has been given an IP address of 10.10.11.159 the router is 10.10.11.1 but I can't ping the router and I can't get any access to the network! I have a SCO Openserver server on the same physical box and it works fine so I know the network card & cable is ok.
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Jan 24, 2011
This dhcp server is configured with redhat enterprise edition. I found that logs are generating in the following path /var/log my doubt is how can i setup the logs generating for a specified day.
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Jun 5, 2010
I decided to forgo my router's DHCP capabilites and try to make a random computer at my home take on the job.
First of all here's my network topology:
I have a cable modem hooked up to eth0 on my linux box, and this is where my internet comes from and works fine.
I also have another ethernet, eth1, which is connected to a wireless router in bridge mode. My end goal is to have my linux box sit between my internal network and the outside world. Thus it will need to act as a DHCP server, a NAT and as a firewall. Right now I'm just focused on the DHCP part.
Here is a copy of my dhcpd.conf file:
My /etc/sysconfig/dhcpd file has:
However the issue is that it is still listening on eth0. and not issuing any leases on my internal network.
What I think is happening is that it's not recognizing the 10.0.1.x subnet because my router is issuing leases on the 169.254.193.x, even though I put it on bridge mode. But I could be totally off mark.
Also running tcpdump on eth1, I can see requests coming in for dhcp, but my server isn't responding to them.
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Jan 19, 2010
I'm trying to get a dhcp server running on my laptop. I want devices to be able to connect to a wireless AP I've set up (using hostapd) to then connect to the rest of the internet via my ethernet connection from the laptop.
However, I can't get dhcp to work properly. It always fails, leaving this message in the syslog
Code:
Jan 19 15:49:15 lucid-laptop dhcpd: WARNING: Host declarations are global. They are not limited to the scope you declared them in.
Jan 19 15:49:15 lucid-laptop dhcpd: WARNING: Host declarations are global. They are not limited to the scope you declared them in.
[Code].....
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Oct 20, 2010
I have a MacBook Pro running VirtualBox with Ubuntu 10.10 as a guest. I am trying to run a DHCP server from within the Ubuntu VM. I need to do this in order to run a multicast utility. On a stand alone machine running Fedcora I have this working without fail but within the Ubuntu VM I am having troubles. The DHCP server is starting okay, but when I use a cross over cable connected to a device the device does not ever get an address.I have eth1 bound to my ethernet jack where I am trying to source the addresses, and eth2 bound to my airport which is disabled unless I need internet access.Here is my DHCP.conf file
Code:
###############################################################################
# Amino Communications Sample dhcpd.conf file #
[code]....
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Feb 12, 2011
My Ubuntu server is now providing routing duties to my network, but I'm having trouble opening ports to my network. I have a DynDNS account, so the IP is always current, but I can't ping even my IP directly.
My network map looks like
Internet > SpeedTouch DSL modem with DHCP > eth1 > Ubuntu > eth0 > LAN
With the modem providing a 192.168.1.xx IP to eth1, I can browse fine. The default gateway is my modem. I switched to the public IP of the modem so I could use iptables for firewall duties, but I was locked out of the internet. No gateway was set when I did that, but eth1 received the public IP of my modem.
How can I use the public IP assigned to eth1?
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Jan 7, 2009
I'm attempting to set up a server for performing diskless boots here. I'm using Gentoo 2008, and have followed the instructions here:
[URL]
I've gotten to the end of the basic DHCP setup, and I can not get the server to issue addresses. I've confirmed dhcpd loads up OK, and is running in top.
Here's the contents of /etc/dhcp/dhcpd:
Code:
# Disable dynamic DNS
ddns-update-style none;
# Assume one default gateway for IP traffic will do
[Code]....
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