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 10.23.1.0/24 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.
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 (76.164.173.2). 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. **
I have a network with multiple subnets from 10.12.056.0 to 10.12.060.0 using net-mask 255.255.248.0 and one gateway 10.12.056.1. 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.
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?
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?
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.
I am attempting to get this network card running under CentOS 5.2 but have had no luck. Some sites say to use the sk98lin driver, others the skge, which I can't find at all. I have tried multiple versions of the driver in rpm but none seem to work. The card shows under the network manager but will not get an IP address from the DHCP server.
Here are the outputs for this card. uname -rmi 2.6.18-92.1.10.el5 x86_64 x86_64 lspci -m 04:01.0 "Ethernet controller" "D-Link System Inc" "DGE-530T Gigabit Ethernet Adapter (rev 11)" -r11 "D-Link System Inc" "DGE-530T Gigabit Ethernet Adapter (rev 11)" lspci -n | grep "$(/sbin/lspci | awk '/net/ { print $1 }')" 04:01.0 0200: 1186:4b01 (rev 11) lspci -vv 04:01.0 Ethernet controller: D-Link System Inc DGE-530T Gigabit Ethernet Adapter (rev 11) (rev 11) Subsystem: D-Link System Inc DGE-530T Gigabit Ethernet Adapter (rev 11) Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop- ParErr- Stepping- SERR- FastB2B- Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- Latency: 64 (5750ns min, 7750ns max), Cache Line Size: 32 bytes Interrupt: pin A routed to IRQ 121 Region 0: Memory at febfc000 (32-bit, non-prefetchable) [size=16K] Region 1: I/O ports at e800 [size=256] Expansion ROM at e0000000 [disabled] [size=128K] Capabilities: [48] Power Management version 2 Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0+,D1+,D2+,D3hot+,D3cold+) Status: D0 PME-Enable- DSel=0 DScale=1 PME- Capabilities: [50] Vital Product Data
How to get this working as we have 3 of these cards for computers without a Gb NIC and I don't want to fight with it 3 separate times.
I'm trying to make a DHCP server work on my CentOS 5.4 box, but I have placed it on another subnet than the one that it is going to serve. I use a helper address on my router to make the the DHCP requests being routed to the DHCP server on the other subnet.
I got a CentOS server setup as a dhcp server using dnsmasq. I followed this guide more or less: [URL] So, the problem seems to be concerning the DNS server on the clients. In windows I get the "limited connectivity" icon for the network, and when I select troubleshoot it says the DNS server does not respond. Issuing 'ipconfig /all' clearly shows the IP of the CentOS machine as the DNS server, which should be correct, yes?
ETH0 is working as WAN connection and that works great.. no problem with the WAN connection at all on the CentOS machine. ETH1 has the IP 192.168.0.1 and mask 255.255.255.0 When starting eth1, it sometimes says that it can't start eth1 because the IP 192.168.0.1 is already in use.. but that is most certainly not the case. Maybe there's some kind of issue here that messes with the DNS? What's mind boggling is that it works great on a linux machine (dhcp client) and on a windows xp machine. but it does not work on the windows 7 laptop and a vista laptop and a pda device.
configuring DHCP server with two NICs. I need DHCP server with 2 NICs:
eth1 - 192.168.103.11 eth2 - 192.168.123.11
The client also has two NICs and suppose to receive ip addresses eth1 from 192.168.103.0 and eth2 from 192.168.123.0 Here is the dhcpd.conf from dhcp server:
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.
I'm looking for a way to configure DHCP client so it would dynamically set the hostname and register itself to a DNS server. I don't have access to the DNS server.
I have tftp-server running on Centos 5. Clients which are on the same subnet as the server are able to get and put without problems. I have a client that is across the internet that is having trouble getting files from my tftp server. A tcpdump reveals that the client is requesting the same file over and over again. In /var/log/messages, I am see the following error repeated over and over until the client finally gives up.
localhost in.tftpd[12727]: tftpd: read: No route to host
I have TWO L3 + router switch (say switch1 and switch2). I created VLAN100 with VLAN ID 100 in both the switches. I created router 192.168.1.1/24 in Switch1. I created router 192.168.2.1/24 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 192.168.1.100(x) to ping PC with IP 192.168.2.100(y)?What 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 (192.168.1.100) to switch2. Move PC (192.168.2.100)to 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?
- 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:
Code: Host 10.0.217.* StrictHostKeyChecking no UserKnownHostsFile /dev/null
I have openvpn tunnel setup between two CentOS servers. One of the CentOS servers also acts as a DHCP server for some client computers.
Server A= OpenVPN server Server B= OpenVPN client (connects to Server A with OpenVPN)
The two CentOS servers can ping each other (172.16.0.0/24) via the tun0.
However, client computer connected to Server B (DHCP server) can't reach 172.16.0.1 (which is the OpenVPN server).
I think I am missing some routing in my "ip route show". Following is the full picture:
What command can I issue to get this fixed? something along ip route add?
There is no firewall service on both end. service iptables stop! I can't bridge eth1 and tun0 as DHCP server might mess up the other side. I can't do a push of "redirect-gateway def1" because then clients loose their IP as they send DHCP requests to Server A.
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 (192.168.0.0/24) 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)?
My company hosts five Servers with CentOS 5 installed in a Data Center. The Data Center assigns a VLAN to each customer so that they can organize customers and also count traffic. The VLAN assigned to my company is in the form 62.103.X.X with a subnet mask 255.255.255.240 so the IPs that we can use in our Servers are 13. The first IP in the VLAN (for example 62.103.1.1) is the Gateway and the rest, that are calculated from the subnet mask, are assigned to servers(62.103.1.2 up to 62.103.1.14).
The problem I have is that we have run out of IPs in our VLAN. We have used all IPs and we want some more. The Data Center can assign new IPs but not grow our VLAN IPs by expanding the subnet mask. So they gave us a new VLAN with some IPs (for example 62.104.X.X with a subnet mask 255.255.255.192) They told me that I had to use as gateway the gateway of the first VLAN 62.103.1.1 and assign the new IPs as usual. So I assigned to one of the CentOS 5 servers the IP 62.104.1.2 and set the gateway to 62.103.1.1. Unfortunately this did not work and we could not establish connectivity to the Internet.Is it possible to assign a gateway outside of the IPs that are in the subnet? Could it be a problem with the VLAN setup by the Data Center?
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.
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.
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?
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.
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
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.
After pinging 192.168.0.106 (106 is on and other host can ping it), arp -a shows ? (192.168.0.106) at <incomplete> on eth0 I tried different ways by disabling the firewall and and disabling SE protection. No Luck.
I will try to explain a bit first about my network typology: I have one cent os 5.5 machine with 2 nics - external one 86.x.x.122 and internal one with 2 IPs: 192.168.1.1 and 89.x.x.121. The ideea is that I have a public subnet (86.x.x.120/29) of IPs which are routable only through 86.x.x.122 so I have a webserver hosted on a different machine with the IP of 89.x.x.122 and GW 89.x.x.121 - everything works perfectly fine, except that I cannot access from the internal network 192.168.1.0 / 24 the so called DMZ (roughly) - the 89.x.x.122.
What really makes me crazy is that I setup the IPtables rules correctly because I can access the webserver from the outside world but I cannot accessit from the internal network...
what I'm missing - why the 192.168.1.0/24 cannot see the 89.x.x.122 machine... What IPtables rules should I add?
I would like to setup 2 linux machine each with two ethernet cards, and need to connect to two subnet e.g. 192.168.*.* and 10.0.*.* . If one linux machine out of order, the other will take over all the services(1 httpd and two named(192.168.*.1 and 10.0.0.1 as server ip). What network config is best and easy to failover to other machine?
I have an Edubuntu server with two nics joined to the primary windows domain and I can log on with domain credentials and everything is AOK. I used LikewiseOpen 6 to join the server to the primary domain. So, on my Edubuntu server eth1 is connected to the primary domain and has a static IP. eth2 also has a static IP and is the DHCP for the thin client subnet, connected to a switch. IP forwarding is enabled.
So far, so good: I can log on the thin clients with one of the local accounts specified on the Edubuntu server and with that account I can surf the net and, if I supply domain credentials, browse the primary domain. Problem I have is:
I can't work out how to log on to the primary domain with a Active Directory account directly from a thin client. If I try DOMAINuser to log on, after giving the password, the password screen refreshes and 'domainuser@11.*.21.*'s password' appears under the blank password box. The IP in that message is the IP for the subnet and not the primary domain. I feel like I'm miss-understanding some basic simple step but I just can't figure it out.
