Networking :: DHCP - Creating Multiple Subnet Pools For Different Hosts?

Jul 16, 2010

I am trying to configure dhcpd to provide two different pools of IPs- one for dynamically named hosts specific to MAC addresses, and another for everyone else.So, a machine with X MAC address connects, gets an IP from e pool, and the server updates DNS with the address under a specific hostname.For the other pool, it just assigns the IP, no DNS updates.The "class" function doesn't appear to allow anything but pattern matching, and I can't find anything that specifies what "allow" and "deny" options therere for the pool command.Here's my config so far - will this do what I want?

key dhcpd {
algorithm hmac-md5;


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Networking :: Config DHCP For Multiple Subnet?

Jun 21, 2010

I have a network with multiple subnets from to using net-mask and one gateway I want to setup a dhcp server and wonder how should I config it? All the hosts in the network using the same net-mask and gateway.

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Networking :: ARP Does Not Resolve MAC Address Of Hosts On The Same Subnet?

Jul 26, 2011

I just changed my CentOS server from DHCP to static IP address. After the change, I cannot ping other hosts on the same subnet. (I can ping the CentOS itself).The IP address of CentOS is pinging (106 is on and other host can ping it), arp -a shows? ( at <incomplete> on eth0 It looks ARP cannot resolve MAC address of hosts

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Networking :: Centos Cannot Ping Hosts On The Same Subnet After Change To Static Ip

Jul 26, 2011

I am using centOS 5.0. After I change from DHCP to static IP address, I cannot ping hosts on the same subnet. The error message says destination host unreachable. Before I made the changes I was able to ping and now even I change it back to DHCP I still cannot ping with the same destination host unreachable message. The centOS is running on VMware on a Windows host.

ifconfig shows

eth0 Link encap:Ethernet HWaddr 00:0C29:A1:9A:10
inet addr: Bcast: Mask:
inet6 addr ......

After pinging (106 is on and other host can ping it), arp -a shows ? ( at <incomplete> on eth0 I tried different ways by disabling the firewall and and disabling SE protection. No Luck.

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CentOS 5 Networking :: DHCP Multi-Subnet From Single Server?

Oct 24, 2010

I've got a bit of a question. My network is laid out like this:

The role assignments are thus:

Firewall - sorts out the passing through to the 3 different networks, and acts as the traffic proxy.
Windows 2003 server - Does Active Directory and DNS
CentOS server - FTP and DHCP

Now, my problem is I need the CentOS server to be able to assign IP address to both networks, however, the CentOS server can *ONLY* be connected via the one interface to the firewall. It needs to assign the Windows 2003 server and the eth0 of the firewall an IP address via static DHCP, but it also needs to able to assign the clients dynamically via any address in the range. I was thinking that I would be able to create static only assignments for the servers via their MAC addresses, and only have 1 dynamically assignable entry for the clients, and then get the firewall to allow ports 67 and 68 to flow freely between eth0 and eth1, but I wasn't entirely sure of the best way to do all this.

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CentOS 5 Server :: Creating A Squid Config With 2 Delay Pools?

Aug 1, 2011

We have a squid-proxy configured with 1 delay pool to limit the bandwith to 6M. I have to create a kind of exception for a specific
remote host for which we want to reserve 1M which is not included within the 6M. How should I do that? Here is our actual configuration of the delay pools

acl all_network src
delay_pools 1
delay_class 1 1


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Networking :: Manually Maintaining /etc/hosts When Using DHCP??

Feb 17, 2010

I have set up a home network using a modem/router, which my devices connect to via ethernet and wireless. I have got it working but i'm still not happy (stick with me...)!

I have settings configured so as to utilise DHCP, so IP addresses for the different machines are automatically assigned by the modem/router (as i understand it). I then obtained these auto-assigned IPs by running ifconfig on each device. I tested connections between the devices by pinging each other using these IPs (ie ping

BUT I want to be able to use hostnames (ie ping dandelion) instead, and the only way I can make this work is to add hosts and corresponding IPs into the /etc/hosts file.

I have made it work in this way, but doesn't this method defeat the idea of DHCP, as I will now presumably have to manually maintain the /etc/hosts files on each device.

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CentOS 5 Networking :: Multiple NICs On The Same Subnet?

Mar 30, 2009

I have a motherboard which has 4 x 1Gbps Ethernet controllers. I would like to use it as a Gateway for my home network. I have a static IP from my ISP which I can use to configure eth0 (I haven't done it yet as the LE-565 is currently sitting behind my Netgear router until I've got DHCP working). I would like to use eth1, eth2 and eth3 for my LAN. How do I set things up so that DHCP is handing out IP addresses on the same subnet ( on all three interfaces?

P.S. I think what I'm asking is: how do I combine all 3 interfaces to behave like a switch (ie. just like my Netgear router)?

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Fedora Networking :: Multiple NICS In Same Machine In Same Subnet?

Dec 7, 2009

I have a program that attaches to an interface. I can run two copies of the program on two systems (each running one instance), connect it to a switch, say & In this configuration two instances of the program can communicate and everything is fine.Now, to reduce cost, it want to use only one system with two nics connected to the same switch, running two instances of the above program, each instance attached to two interfaces respectively on the system. I have the following settings:

eth1 Link encap:Ethernet HWaddr XXXXXXXXXXXXXXX
inet addr: Bcast: Mask:


However I cannot ping one from the other.

Neither "ping -I eth1" nor "ping -I eth2" works.

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Ubuntu Networking :: Multiple Ipv6 Routers On A Subnet?

May 6, 2011

I have a 6to4 tunnel running on Ethernet (subnet 2002:ad4c:16cc:1) without problem. It runs radvd and announces a default route back to the Internet like this: "default via fe80::6a7f:74ff:fe0a:fbec dev br0"

On this same Ethernet I have a Linux plugbox (fe80::225:31ff:fe01:cc) which is a gateway to a network of IPv6 enabled sensors. I've assigned this second subnet 2002:ad4c:16cc:2. How do I get the plugbox to announce "2002:ad4c:16cc:2 via fe80::225:31ff:fe01:cc" so that the hosts on the Ethernet (2002:ad4c:16cc:1) will automatically pick up the route? The route works if I add it to the boxes manually. I've tried getting radvd on the plugbox to do this but I've had no success.

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Networking :: VLAN With 2 Router And 2 Subnet - Is Device In Different Subnet Works

Jul 22, 2011

I have TWO L3 + router switch (say switch1 and switch2). I created VLAN100 with VLAN ID 100 in both the switches. I created router in Switch1. I created router in Switch2. Switch1 is connected with 1.x/24 PCs. PCs are configured with 1.1 gateway. Switch2 is connected with 2.x/24 PCs. PCs are configured with 2.1 gateway. Both Switch1 and switch2 are connected by a trunk to carry VLAN100 data.

1)I have few PCs of 1.x connected to say Switch1 Is it possible for PC with IP to ping PC with IP are the configuration required in both switches to make them communicate ? All the device in both the subnets should ping/communicate with each other.

2)Move PC ( to switch2. Move PC ( switch1.What will happen when PC(1.100) ping (2.100) and vice versa?What will happen when PC(say 1.80 in switch1) pings PC (say 1.100 in switch2) and vice versa? What will happen when PC(say 1.80 in switch1) pings PC (say 2.100 in switch1) and vice versa?

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Security :: Disable StrictHostKeyChecking For A DHCP And DNS-using Subnet

Dec 28, 2010

I have a VMware farm where:

- DHCP is in use to give machines IPs
- Machines go up and down all the time
- All IPs are on a certain subnet
- VMs update DNS (we don't go by IP)
- SSH is in use

I would like to disable StrictHostKeyChecking only for this subnet, because IPs change all the time and editing known_hosts usually only works for a few days before the IP changes again, and once I get enough entries, there are tons of conflicts.

I tried the following in ~/.ssh/config:

Host 10.0.217.*
StrictHostKeyChecking no
UserKnownHostsFile /dev/null


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Networking :: Can't Browse Computer Of One Subnet From Another Subnet

Jul 4, 2011

I installed Redhat Enterprise linux server5. it has two LAN card and two subnet connected to these two LAN card. i can browse network from these two network easily. But i created VLAN on one network card.Now i cant browse network from these VLAN subnet.

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CentOS 5 Server :: DHCP Config ( No Subnet Declaration For Eth0 )?

Apr 1, 2011

I had a server that I use for Radius DNS and Trying to put DHCP on it I have My pool in it seems right. I have 2 adresses aliased one being a helper IP that the router will send the request to. When I try to start the dhcp server I get the following.

Mar 31 14:33:11 rad2 dhcpd: No subnet declaration for eth0 (
Mar 31 14:33:11 rad2 dhcpd: ** Ignoring requests on eth0. If this is not what
Mar 31 14:33:11 rad2 dhcpd: you want, please write a subnet declaration
Mar 31 14:33:11 rad2 dhcpd: in your dhcpd.conf file for the network segment
Mar 31 14:33:11 rad2 dhcpd: to which interface eth0 is attached. **


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Ubuntu Servers :: Apache2: SNI & Virtual Hosts - Multiple Virtual Hosts With Ssl And Only 1 Ip Address

Jan 17, 2011


What I want: multiple virtual hosts with ssl and only 1 ip address: In my example: server =


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Networking :: Multiple DHCP In One Large LAN?

Dec 6, 2010

I've searched on issues of multiple DHCP servers in one LAN. Just about everything is Windows or Novell based stuff. Also, the typically asked scenario is 2 or more DHCP servers for failover purpose (one goes down, the other takes over).

What I want to do with DHCP is different. My purpose would best be described as "administrative separation". Basically, if a given MAC address is configured on a specific DHCP server, that server should be the one to answer and not the other. The problem with that is that we also need a default to handle unknown MACs. So the DHCP server without the MAC configured would be answering, anyway, even if it is the only one configured to do global leasing. Timing would then be the determining factor.

The purpose is to set up a bunch of PXE network booting using program generated DHCP configuration. This server won't always be up, so it can't be used for general purpose. The DHCP server for general purpose is part of a wireless system, and it is configured by GUI and is impractical for the programmed PXE booting.

how to make these work together with everything being on the same LAN segment?

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Ubuntu Servers :: Config DHCP Server To Assign A Different Subnet For VPN Users?

Apr 4, 2010

I'm establishing a server that runs DHCP server, NAT gateway and VPN server. It have two physical interfaces, one for intranet and one for internet. The NAT gateway will give internet access for intranet. Another site will connect to this server by VPN. I need the server to assign a different subnet for that site other than the local site. Do anyone know how to config the DHCP server? Should I config the client classing, and how to do it?

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Networking :: DHCP Script - Assigning Multiple IP Addresses By Mac?

Sep 6, 2010

Ive been trying to give certain clients an IP adres by mac adress. For this I use the folowing code:

host apex {
hardware ethernet 00:00:00:00:00:00;

This works perfectly, however when I try to add a second client this way it doesnt. I tried to add the above code multiple times as a whole (2 times the above code) but that doesnt work. I also tried to just add more lines under host apex but this also doesnt work.

So my question is: How do I add more of this mac related IP adress assignments in the dhcp.conf?

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Networking :: Use Multiple Dhcp Subnets On Single Machine?

Dec 13, 2010

I am find myself in need of building what amounts to 3 ip networks on 1 physical lan.

first LAN is another companies network on the network a mix of pc's and equipment

second is LAN new company network

third network is an ip phone system for both i would like to use

i am hoping to use the same dhcp server to do this, assigning address to the old company's 10. network via mac address reservation.

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CentOS 5 Networking :: DHCP Server To Serve Multiple Networks?

Dec 11, 2009

I was just wondering if someone could tell me the best method to connect all my hardwares together to achieve better result.HARDWARES.Cable ModemNETGEAR ROUTERNETGEAR FS728TS Smart switchLINUX SERVER WITH 2NICS.I want my dhcp server to serve 3VLAN networks. I need someone to show me how to do this. What do I need to do. keep in mind, I want eth0 to be used for public address only while eth1 for LAN. DHCP will be on eth0, but I need LAN on eth1 to be relayed back to eth0. This is my school project.

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Networking :: Creating Own Network Program For Multiple OS

Nov 19, 2009

I have some novice to intermediate programming skills from a past life. What I want to do is create a program and run it on two separate computers to just get them communicating together over the network on a basic level. I would like to do this in a language that doesn't limit me to a specific OS, this way I can have a linux and windows computer talking. However, I would prefer a language that can be useful down the road as well. My second inspiration, next to networking, is web design and web programming, which I hope to dig into as well eventually.

I'm not aiming to do anything overtly-complicated. One example that comes to mind would be a program that forwards any typed characters on one computer over the network and displays them on the other, and vice-versa. I guess the program would run over TCP/IP. However, it would be nice to learn how to do this in a language that not only works on multiple OSes, but also has the ability to allow me to program my own communication protocol, aside from TCP/IP, down the road. My intention with all this is to learn some network programming for fun.

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Networking :: How To Apply Delay Pools On Squid

Mar 7, 2011

I am using squid 2.6 on my cent os 5.We r using 4 Mb/s link. I want to assign bandwidth allowcation to my boss like 512 Kb/s and 256 kb/s to its assistant.both are using class c IP address. How can I allocate bandwidth of their IP address.

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Ubuntu Networking :: Proxy Settings: Allowed Hosts Instead Of Ignored Hosts

Aug 17, 2011

Well, as many proxy applications, GNOME Network Proxy Preferences only allow to ignore hosts. What I want to do is exactly the opposite. I only want to use the proxy for few sites. Is it possible to define only the allowed hosts in any way?

PS: I know FoxyProxy add-on for Firefox does this, but 1)I don't use Firefox and 2)I want the proxy settings system wide not only for browser.

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Networking :: CentOS 5 System With Squid 2.6 - How To Enable Delay Pools

Apr 2, 2011

I have install squid 2.6 in my cent os 5 system. The proxy server is working perfect using the following method.
[root@localhost squid-2.6.STATBLE22]# ./configure@--prefix=/usr/local/squid

I want to enable delay pools feature in it.For that purpose I do as following
[root@localhost squid-2.6.STATBLE22]# ./configure --enable-delay-pools && "configuration successful"

The question is should I configure it as I do it for squid
./configure --enable-delay-pools--prefix=/usr/local/squid
To enable delay pools may I need the correction in the steps which I have taken.
[root@localhost squid-2.6.STATBLE22]#make
[root@localhost squid-2.6.STATBLE22]# make install

In short to enable delay pools may I just use
# ./configure --enable-delay-pools
#make install

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Programming :: Ssh Command On Multiple Hosts?

Apr 13, 2010

I want to create a script to insert the fstab and hostname in a textfile of multiple servers on the network without a password. The servers are situated in a text file. So i want to read the text file line by line and write the output into another textfile.

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Server :: Configure Multiple Smart Hosts?

Mar 11, 2010

We have a requirement to configure multiple email gateways, for mail accounts configured on linux server. the application will trigger mails (bulk mails) and we would like to configure multiple email gateway to be used.

we decided to do it this way.

In dns we would create MX records like 3600 IN MX 20 3600 IN MX 20

where and will be our email gateway.

and internally on our linux server (from which mail is sent) if i specify multiple smart hosts like


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Server :: Set Up Multiple Name Based SSL Hosts On A Single IP?

Feb 27, 2011

have a look at the following thread story and please clear my doubt.

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Server :: Synchronizing /etc/hosts Files Across Multiple Servers?

Jun 16, 2011

I have 16 linux servers that use /etc/hosts files to see and talk with each other. I'm adding servers to this pool of servers. It is required to do host resolution via the /etc/hosts files. DNS or NIS are not alternatives. Aside from manually editing each of the 16+ /etc/hosts files every time I add a server or editing one /etc/hosts file on one server then scp'ing it to all the other servers, is there anyway to edit the /etc/hosts on one server and "push" it onto the other servers that need the new /etc/hosts file?

Everywhere I've looked on the Net, there hasn't been any suggestion except for the options I mention here.

Or am I just whistling in the wind?

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Ubuntu Servers :: Multiple Virtual Hosts, Http And Https?

Sep 15, 2010

What is the best way to go about setting up multiple virtual hosts on the same box, one using http and one using https/ssl? I'd like to serve them from the same ip address if possible; I know it's possible in apache 1.3.

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General :: Sun Grid Engine - Reserve Multiple Cpus On Hosts

Mar 14, 2011

I am somewhat familiar with SGE (Sun Grid Engine, now Oracle Grid Engine) commands but am having a problem when running parallel jobs.

Present Machine configuration:
machine I - 12 cpus
machine II - 12 cpus
machine III - 12 cpus
.... so on ...
One_machine - 16 cpus

(I have all machine of 12 cpus and 1 machine having 16 cpus)

I want to schedule jobs on these machine such that if I ask for 12 cpus - my jobs should execute on any of the machines which has all 12 free cpus (eg machine I or machine II) in this case.

Eg. suppose I ask for 24 cpus

Option I : 12@machine1 12@machine2 ----- I need this

Options II : 10@machin1 10@machine2 4@machine3 ---- I don't need such a distribution

Hence, Option I is ideal here. Also, when running 12 jobs on machine1 (say) - even if all 12 cpus are not being used at some instance of time, none of the 12 cpus should be freed.
In short, until my run finishes, all blocked cpus should remain blocked.

If you may understand, the purpose here is to run some performance tests.

I'm using 'qrsh' to launch jobs.

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