Networking :: Isolation On A Non-router Server With Multiple Ethernet?
Jan 12, 2011
I have been working with Linux for about 10 years and I have a good understanding of IPv4 networking and routing but not so much detailed knowledge of implementation or specific networking packages.
I have a Linux system running a custom-built (Linux from Scratch) distribution and using 2.6.15 kernel. My system has 4 Ethernet controllers (eth0, eth1, eth2, and eth3). I have intentionally left out support for forwarding/routing of packets as this machine is not intended to be a router and I specifically do not want it to be able to so. My intent for the machine is to function as a server to 4 different and separate networks without allowing traffic or hosts on one LAN to access or adversely affect those on the other LANs.
My main question: is there a way to completely isolate the connections to these LANs and if so, how might I achieve it, and through what packages?
I have been having some issues:
1) Default gateway. With only a single default gateway, network requests from a LAN that is not directly connected to one of the 4 NICs and for which there may not be a static route defined, may send a response to the default gateway which is on one of the LANs connected to a different NIC than the one that I received the initial request on. Is there anyway to isolate outgoing messages to only go out on the NIC that the corresponding request was received through?
2) Default gateways. I have a requirement to allow DHCP on these interfaces. It is possible that the DCHP servers on each of the 4 LANs may provide a default gateway, but I don't see how I can make use of that. I know that there is a way to configure multiple default gateways via the iproute2 package (which is what I am using) but I don't know how to make sure that the correct default gateway is used for requests that were received on a specific interface.
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Sep 2, 2010
I tried to setup a connection as below but face some problem (probably route table setting incorrect). Hope if anyone could shed the light.Basically, I have a PC1 (.1) and PC2 (.130) connected via a PC router. PC router has 2 interfaces: wireless (.2) and ethernet (.129). PC1 connects to PC router via LAN cable/wireless interface, while PC2 connects to PC router via cable. This settings try to simulate 1 wireless connection along the path (and because PC2 is too old to support wireless interface, we need a PC router). These interfaces are all under same 172.16.130.x subnet.
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Jan 16, 2011
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Mar 1, 2010
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Dec 20, 2010
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Dec 5, 2010
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May 27, 2011
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Jul 9, 2011
the title says I have painfully slow(connection times out when loading google) ethernet connection on my new pc. This comp had similar problems with the OEM windows 7 install but now it's strictly a linux box so I'm anxious to get it fixed.
I'm running Ubuntu 10.04 and Slackware 13.37, and have wireless working on Ubuntu but haven't set it up on Slack yet. The only thing I've done so far is try to change speed and duplex using ethtool but it didn't work, the settings stayed the same. I'm writing from another comp so I'll do my best to post any info you request but I'll have to use a flash drive lol
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Dec 12, 2010
I have 2 LAN ports. one from the motherboard (on board) and the other from a lan card i bought a few days back. one is use for browsing the net, the other for a media player.
problem is i cant connect to both the eth0 and eth1 at the same time. i have to disconnect one of them to connect to the other. and this really gets irritating as it doesnt always work as flawlessly as it should. what am i doing wrong?
Output of "ifconfig":
Quote:
I'm on ubuntu desktop 10.10 64 bit.
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Aug 14, 2010
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Jan 14, 2011
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May 2, 2011
I'm looking with some multiple WAN links on an Ubuntu router box I am building for a project.The setup I'm trying to achieve is this:
eth0 WAN Link 1 through ADSL modem
USB Modem 1 WAN Link 2 for Failover
USB Modem 2 WAN Link 3 for Failover
[code]...
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Feb 16, 2010
I recently installed Ubuntu Server 9.10 with the intent of using it as a platform for running a couple of Windows XP virtual machines along with Linux/Ubuntu.
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What Im having trouble with is figuring out how to bridge from multiple VMs AND Ubuntu natively through one physical ethernet card.
When I set up the bridge, it knocks out the static IP address of the ethernet card that was set up initially with Ubuntu when first installed before the VM was created and installed. Therefore, connectivity within Ubuntu natively is lost.
Similarly, am having trouble figuring out how the second VM (also going to be running WinXP) is going to get its connectivity since it doesnt seem to like me setting up 2 bridges to the same physical ethernet interface card.
I need all 3 machines to have static IP addresses and be visible/accessible from the external network for either web/mail/dns/etc servers on the Ubuntu side and for remote PC control functionality on the VM side.
I have tried setting up alias ethernet interfaces (eth0:1, eth0:2, eth0:3) with static addresses which work fine from native Ubuntu in presenting multiple IP addressees, but it seems that Im not permitted to bridge to these alias interfaces.
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May 8, 2010
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Feb 3, 2011
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Mar 1, 2010
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Oct 11, 2010
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Jul 2, 2010
I am really interested to configure my old desktop with Slackware 12 as a router. But unfortunately I did not found any other ethernet card (second) as Realtek 8029. (I need two ethernet cards according to the howto [URL]) It is possible to get up and running this card? I was googling a lot. I tried to use the ne2k-pci module. It seems that it was loaded successfully, but I cannot see my interface (eth1) with ifconfig.
lspci shows:
Quote:
00:0b:0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8029(AS)
lsmod:
Quote:
ne2k-pci 12768 0 (used by)
[Code]....
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Aug 27, 2011
I'm having trouble getting my Ubuntu 10.04 machine (Sony Vaio VGN-SR490) to connect to the Internet by way of an Ethernet cable connected directly to my router.
I'm able to connect to the Internet using this same cable using a Windows machine, so there's something wrong with the way Linux is configured.
How do I got about figuring out what the problem is and solving it?
Here are my network settings on Linux:
$ ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
[Code].....
It looks like the network adapters list is empty. I will now install both Windows XP and Ubuntu Linux dual-boot. I'm still not able to access the internet, even through Windows. I'm wonder if this could be a hardware problem with the computer or a problem with the router itself. Other computers can connect to this same router, and work fine. (That's how I'm posting this after all!)
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Jun 30, 2010
I cannot connect to my Ubuntu Server. Currently I'm trying via my MacBook through ethernet. A physical connection is apparent; however, the computers cannot communicate. To resolve this problem is important because I just need basic SSH functionality. While connected through ethernet, my MacBook cannot ping my Ubuntu box. Here is a screen shot of the Mac's network setup, a ping attempt, the ifconfig's of both machines.
[Code]...
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Jul 18, 2010
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Sep 1, 2011
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Oct 5, 2010
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Jan 5, 2010
Using SuSE 11.2 can anybody suggest a decent compatible Ethernet / Network Colour Printer. Just a printer not a multifunction device. The printer will be connected to a Fast Ethernet Switch or directly into the ADSL Router.
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Mar 2, 2010
i already have an eth0 configured to automatically get its info from dhcp.
but i wanna configure eth1 to be able to serve dhcp and dns. i havent configured either dns or dhcp server on the server box since i have not configured the serving interface.
so far my interfaces file is:
Code:
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet dhcp
[Code]....
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Aug 13, 2010
I am using Ubuntu 10.04 Lucid and VMware 2.0 server. I have a an XP virtual machine that is needed for work. When I am at home and I place my cat 5 cable to my cisco catalyst switch, my XP VM recognizes the ethernet card on my laptop and bridges fine with ubuntu and works fine and I can get to my network. When I take my laptop to work and I go to a site and I plug it into a World Wide Packet 311 management port on the switch, my XP Virtual Machine does not see the network no matter what setting I set it too(100 full, 10 full, 10 half and etc). It simply says that the network card is disconnect. Ubuntu see the network fine and I can ping and talk to the network without any issues but the VM does not.
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Jul 14, 2010
I've got a machine running Ubuntu Server that is on several VLANs. Each VLAN has its own subnet and the server has an address on each subnet. The switches are set to allow tagged traffic to the server for each VLAN that it is on. Switch ports ending with workstations are given untagged ports on whatever VLAN is appropriate. Workstations are given addresses on a subnet for each VLAN via DHCP. All this works great and hosts on any subnet/VLAN can access the server as normal via its address on that subnet/VLAN.
Accessing the machine by its address on a non-local subnet is where I run into a problem. Inter-subnet traffic has to go through a router, which has been set up appropriately. Running tcpdump on the server and pinging it from a workstation on a subnet, using its address on a different subnet, shows the server receives the ping, but sends no response:
Code:
sudo tcpdump -i vlan4 -n
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
[code]...
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Nov 17, 2010
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