I have two NICs.
On eth1 IP is 10.135.28.86/16.
On eth IP is 135.251.8.43/24.
My routing table is like below:
135.251.8.0/24 dev eth1 proto kernel scope link src 135.251.8.43
10.135.0.0/16 dev eth0 proto kernel scope link src 10.135.28.86
169.254.0.0/16 dev eth0 scope link metric 1002
169.254.0.0/16 dev eth1 scope link metric 1003
10.0.0.0/8 via 10.135.0.1 dev eth0
default via 135.251.8.1 dev eth1
Now if I ping 10.135.28.86 from 10.34.7.103, it's OK, while if I ping 135.251.8.43 from 10.34.7.10, it fails.
And if I ping my public IP 135.251.8.43 from 135.252.11.7, it's OK, if I ping 10.135.28.86, it fails.
However, on my other machines which have exactly the same subnet and gateway configured, I can ping both IP either from 10.34.7.103 or 135.252.11.7.
Any ideas on this?
I used tcpdump to capture icmp packet on other machines and found that echo request come in eth0 and echo reply out from eth1.
but on this machine no echo reply were captured.
When you ping from your other machines with IP's in both networks the machine uses the interface on the same network to send the packet (so private-to-private and public-to-public, since they are on directly connected subnets). That is why it reaches, they are on the same subnet.
I see 2 scenarios.
1.
The machine which only has IP on your private network (10.34.7.10) probobly sends its ping to dgw (IP?) which then forwards it to 135.251.8.43 (eth0).
But since the source adress (10.34.7.10) is on a network directly connected to it's other interface (eth1) the answer will be sent back there. I would say you have a flawed network architecture.
The machine 10.34.7.10 has a static route for 135.251.8.43 to 10.135.28.86, but your machine has not bridged the 2 networks.
Related
I am struggling with a network problem.
My computer needs to be linked to two differents networks. one via PCI the other one via a USB adapter. The pci is the "usual" network, the usb is to use for specific address.
I have tried differents solutions, with dns, multiple wired connection, modifiying /etc/network/interfaces, ...
But I can't manage to have the 2 networking working at the same time.
Do you have any solution. I am working with Debian - jessie.
Cheers
Since you haven't specified any networks, IP addresses or device names, I will use my machine as an example.
I have an IOGear ethernet USB dongle which shows up as device enx0050b6d341bb, and an RTL811 PCI ethernet device which shows up as eth0. eth0 is plugged into the "main" network which has a DHCP server and enx0050b6d341bb is connected to a private switch on my workbench.
If I want to use eth0 to connect to the internet, but use enx0050b6d341bb to connect to anything on network 192.168.168.0/24, /etc/network/interfaces will look like this:
auto lo
iface lo inet loopback
# Obtain DHCP address from server
auto eth0
iface eth0 inet dhcp
# Connect to 192.168.168.0 network
auto enx0050b6d341bb
iface enx0050b6d341bb inet static
address 192.168.168.3
network 192.168.168.0
netmask 255.255.255.0
Since I only have one device using DHCP, my default route will automatically go through that device, which happens to be exactly what I want :-)
solargy#GEPY633007AX:~$ ip route
default via 192.168.10.1 dev eth0
192.168.10.0/24 dev eth0 proto kernel scope link src 192.168.10.67
192.168.168.0/24 dev enx0050b6d341bb proto kernel scope link src 192.168.168.3
The above shows that my default traffic will go through eth0 and that any traffic for addresses in network 192.168.168.0/24 will go through enx0050b6d341bb. To verify that, you can find out which device will be used to communicate with address 192.168.168.2:
solargy#GEPY633007AX:~$ ip route get 192.168.168.2
192.168.168.2 dev enx0050b6d341bb src 192.168.168.3
cache
As you can see, any traffic for 192.168.168.2 will go through enx0050b6d341bb.
I have two network interfaces (e.g. eth0 and eth1) configured as two ends of a bridge in Ubuntu Linux 14.04. They are not assigned with any IP addresses. eth0 is physically connected to a subnet. I want to send UDP packets through eth0 to a subnet connected machine. I create a UDP socket and check that it can successfully bind to eth0 (i.e. setsockopt(socket, SOL_SOCKET, SO_BINDTODEVICE, eth0, strlen(eth0)), and executing sendto() reports success as well. However, the designated target machine cannot receive anything from eth0!!
Is there any Ubuntu tools/commands to trace where the UDP packets go (actually, I did try to use Wireshark. But, Wireshark cannot detect any network interface to capture!)?
And, is there any workarounds, under the situation that eth0 and eth1 must be set as a interconnected bridge with no IP addresses, to make use of eth0 to send UDP packets to other machine with designated IP address and port?
I have a dual port ethernet NIC and let's say I have connected 2 ports in a loop and assigned the following IPs to the 2 ethernet interfaces:
eth2 -> 192.168.2.1
eth3 -> 192.168.3.1
I want to send traffic from 1 port to another over the physical network, e.g. ping 192.168.3.1 from 192.168.2.1. However, the TCP/IP stack in the Linux kernel recognizes that these two addresses are local and instead sends the traffic to the loopback adapter, so the traffic never hits the physical network.
The closest I have to a solution is Anastasov's send-to-self patch, which unfortunately, has been discontinued since kernel 3.6 so it won't work on Ubuntu 13.10 (kernel 3.11) for me. I've tried finding rewriting the patch for 3.11, but I can't seem to locate these in the Ubuntu distro:
include/linux/inetdevice.h
net/ipv4/devinet.c
net/ipv4/fib_frontend.c
net/ipv4/route.c
Documentation/networking/ip-sysctl.txt
Is there a way I can get the send-to-self patch to work, or an alternative?
You can use network namespaces for this purpose.
As ip-netns's manpage says:
A network namespace is logically another copy of the network stack,
with its own routes, firewall rules, and network devices.
Following is just a copy of this answer:
Create a network namespace and move one of interfaces into it:
ip netns add test
ip link set eth1 netns test
Start a shell in the new namespace:
ip netns exec test bash
Then proceed as if you had two machines. When finished exit the shell and delete the namespace:
ip netns del test
you can try configuring route table, by running "ip" command:
ip route add to unicast 192.168.3.1 dev eth2
ip route add to unicast 192.168.2.1 dev eth3
new route would be added into route table, and it should be able to take effect before egress routing lookup hit the host-local route between "192.168.3.1" and "192.168.2.1", therefore, the traffic should be sent through physical interface "eth2" and "eth3", instead of loopback "lo"
Never tried myself, but should work.
i'm triying to imagine how to do:
(with Linux Debian based distro)
I have PC with 4 NIC:
eth0 = Internet Access (connect to router WAN)
eth1 = Local lan
eth2 = OUT NIC
eth3 = IN NIC
I need to send all traffic from eth1 (local lan) to eth2, receive the same traffic from eth3 and route to eth0.
The idea is send all eth1 traffic to external device over eth2, the external device inspect the packets and send to PC again on eth3, then my PC Linux route traffic to eth0
Is posible to do that ?
You're running linux on a PC? We need to know the version first off. Second you are looking into IProutes if you want to redirect traffic from one NIC to another.
I have to make a STUN server in OpenSIPs, and it says that I need to bind 2 IP addresses.
http://www.opensips.org/About/News0042
A STUN server uses 2 ips and 2 ports to create 4 sockets on which to listen or respond.
STUN requires 2 routable ip addresses
How can I enable two public IP addresses into one Linux server? I've searched all website, and failed to find the answer.
Several options.
Option 1.
You likely just need to use ifconfig from the command line to start
You can assign an additional static IP address to your NIC via the command line. Type ifconfig to get the name of your default adapter. It's typically "eth0". Then do add a secondary address to this adapter, the command is something like the following:
sudo ifconfig eth0:1 inet up netmask 255.255.255.0 192.168.1.55
Where 255.255.255.0 is the netmask of my 8-bit subnet and 192.16.1.55 is an existing IP address that no other device on my subnet is already using.
Option 2.
After you get your server up and running with Option 1, you likely need to find a way to get the IP address assigned by "ifconfig" to persist after a reboot. You could likely stick an ifconfig statement into one of your rc.init files. But most Linux skus have a formal way of configuring an interface with another /etc file. But this step varies between different flavors of Linux. On Ubuntu, this is all defined in the /etc/network/interfaces file. Add these three lines to the bottom of your existing file:
iface eth0:1 inet static
address 192.168.1.55
netmask 255.255.255.0
Option 3 (shameless plug)
Switch to Stuntman ( www.stunprotocol.org ) as your STUN server. Its default mode only requires one IP address to be present on the box. Most client usages of the STUN protocol don't require the second IP address unless to do NAT classification and behavior tests.