TLDR: Is there a way to use "ip route" to add multicast routes for multiple NICs?
We have software that joins two sockets bound to different ip addresses on separate NICS to two separate multicast groups, eg socket 1 is bound to 192.168.0.2 and joined to multicast group 233.255.10.1 while socket 2 is bound to 10.57.31.2 and joined to multicast group 239.255.100.1.
We are currently using a bash script (Linux kernel 3.14.39) to set multicast routes on the two network interfaces using route, eg
route add -net 224.0.0.0 netmask 240.0.0.0 eth0
route add -net 224.0.0.0 netmask 240.0.0.0 eth1
and verified via route -n
Destination Gateway Genmask Flags Metric Ref Use Iface
224.0.0.0 0.0.0.0 240.0.0.0 U 0 0 0 eth0
224.0.0.0 0.0.0.0 240.0.0.0 U 0 0 0 eth1
I recently read that route was deprecated/obsolete and that we should be using ip route instead, eg
ip route add 224.0.0.0/4 dev eth0
ip route add 224.0.0.0/4 dev eth1
Unfortunately, the second call fails with "RTNETLINK answers: File exists" and of course the second route doesn't show up after these calls.
Is there a way to use ip route to add multicast routes to multiple NICs?
I can use /8 as a netmask? eg
ip route add 233.0.0.0/8 dev eth0
and
ip route add 239.0.0.0/8 dev eth1
but this is problematic as the script that does this is not aware of what multicast address is associated with which device and its not always guaranteed to be the same depending on system configuration. Using my first example of route add makes this a non issue.
Related
Let's say I have two network interfaces:
eth0 with address 10.0.0.1
eth1 with address 192.168.0.1
Using route or ip route add I have set it to route:
All addresses to eth0
1.2.3.4 only to eth1
So packets to 1.2.3.4 should be routed to eth1, and everything else to eth0.
I then create a UDP socket and use bind() to set its local address to 192.168.0.1. Then I send a packet to 1.2.3.4.
Will it be be sent over eth1 per the routing table or eth0 because it is bound to that IP address? I tried, and it seems to be sent on eth1.
Is there a way I can force a socket to use eth0, which has a valid route to the destination, but not the most specific rule? I know about SO_BINDTODEVICE, but prefer to avoid using interface names in C code.
For sockets if you want the the Kernel and its routing table to pick the best interface for you using any available port you don't have to call bind() before sending datagram socket.
If you do bind a socket, it will be bound to a network device with that specific IP address. But does it make sense if packet can't reach destination address from that network device?
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.
Route command output:
$ route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.2.10 0.0.0.0 UG 0 0 0 eth0
192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
$
From the above output the following are the doubts I have:
What is 0.0.0.0 means in destination and gateway column
If the packet is sent from 192.168.2.36 ip, what is the gateway for that. It use 192.168.2.10 or 0.0.0.0
Lets consider I have one more network with ip 192.168.1.0. If the packet is sent from any of the host from this network, what is the
gateway for that ip.
What is default gateway.
On the first line, 0.0.0.0 in Genmask means there is no mask, i.e. in combination with a destination of 0.0.0.0, it means all destinations (the default gateway definition). On the second line, 0.0.0.0 in the gateway column means no gateway (directly connected the local subnet).
When routing, it does not matter where you are sending from, but where you are sending to.
Packets sent to network 192.168.1.0 will be routed using gateway 192.168.2.10, since the first line is the only one that matches destination 192.169.1.0.
192.168.2.10 (see answer 1).
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.
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.