My computer has 2 ethernet ports and 1 wireless port. One of the ethernet ports (eth5) and the wireless port (wlan0) are both configured to connect to a network server, and the other ethernet port (eth4) is configured to connect to a local network switch for communicating with some local devices. The route table of the computer looks like this (as I can not post image yet):
Destination Gateway Genmask Iface
0.0.0.0 141.21.32.1 0.0.0.0 eth5
10.10.10.0 0.0.0.0 255.255.255.0 eth4
141.21.12.0 0.0.0.0 255.255.252.0 wlan0
141.21.32.0 0.0.0.0 255.255.224.0 eth5
169.254.0.0 0.0.0.0 255.255.0.0 eth5
My question is that, how I could change the sequence of the gateways with the network-manager in ubuntu (permanently), so that the gateway of wlan0 will be used before the eth4's. Otherwise when I unplug the cable from eth5, I will lose connection to the network (the gateway of eth4 will be used by default).
I tried editing the /etc/network/interfaces file, but it conflicts with the network-manager, and it can not handle the dynamic events (e.g., when network cable is plugged or unplugged), meaning that its settings are static, while the network-manager can handle these things perfectly, and change the network configurations adaptively, so I would like to find a solution for this problem with network-manager.
The os is ubuntu 13.04 32bit. Thanks for viewing and I will appreciate for any advice!
Problem is solved by checking the option "use this connection only for resources on its network" in the "Routes" page of the IPv4 settings of the configuration interface for the local network (used by eth4) in network-manager.
Related
I am on a Windows 10 machine. I have got the below routes configured in my machine.
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 192.168.1.1 192.168.1.5 1
10.1.0.0 255.255.0.0 192.168.2.1 192.168.2.5 1
10.2.0.0 255.255.0.0 192.168.3.1 192.168.3.5 1
When ping IP 10.1.1.1, I want to determine which network interface will be used to route the traffic.
Is there any network utility that can help me find the correct route based on the destination IP?
If you ping 10.1.1.1, it will use the interface with the IP 192.168.2.5 looking at your route table.
You can also use tracert 10.1.1.1 to see what route your network traffic will take.
I have built two VM, and both use the same network configuration which are NAT for the first network adapter, and Host only Ethernet Adapter for the second adapter.
This is my network configuration for both VM :
First VM
eth0 : dhcp
eth1 : 10.0.0.10 255.255.255.0
Second VM
eth0 : dhcp
eth1 : 10.0.0.20 255.255.255.0
How to solve the problem? should i do or reconfigure something?
In VMWare, Host-Only mean VM's can ONLY network with the host, not other vm's. but in Parallel Desktop and VirtualBox it work.
So in a simple way, if you want to block the network between Second VM and Internet, you could choose NAT and set some firewall with iptable on host.
In VMWare website, you should route between Two Host-Only Networks like this link.
There is more information about Host Only Network.
I have two machines, machine A sending packets to machine B.
If I use
tcpdump -i <interface> udp port <port>
on machine A, I can see the traffic going out.
However when I enable the VPN, I then see nothing coming out of that port.
And I would like to understand why.
The VPN is IPsec based which I understand encrypts the packets, and has the tunneling mode as a typical default.
I was going through some stuff on IPsec VPNs and saw it mentioned that the VPN sends the packets out of different ports. I saw port 4500 mentioned in a number of places, as well as some other port numbers.
I did try these port listed but saw nothing at any of them.
Is my issue that I am preforming the traffic dump at the wrong port? If so is there a way to determine which port the outgoing traffic of machine A is leaving from?
If it is another issue, what might it be? Is it possible to monitor my outgoing traffic from a machine with a VPN tunnel enabled?
When you initially capture packets, you are seeing traffic on your default interface (whichever that is). When you enable your VPN, part of the setup process is to make the VPN virtual interface the default interface. Depending on your system, this will mean giving the VPN interface a higher routing metric or higher routing priority in the list.
After you enable your VPN connection, your routing table should change (see below). You should also see the name of your VPN connection with these commands (as new default interface), which can be used as the interface name with tcpdump. Note that depending on your system/VPN solution, you might need to do additional configuration to get the necessary vpn interface name.
Route metrics on various systems
netstat -rn will show you the routing table on most systems (Windows, Macos, Linux, BSD, ...), but won't show you the routing metrics.
The following commands will show you routing metrics (with sample output shown). As you can see, on Ubuntu/Windows, there's a routing metric number, but on Macos, there's a routing ordering. The way you change the routing ordering in Macos is to literally just change the list order like networksetup -ordernetworkservices service1, service2...
Ubuntu 18.04
$ route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.0.2.2 0.0.0.0 UG 100 0 0 enp0s3
10.0.2.0 0.0.0.0 255.255.255.0 U 100 0 0 enp0s3
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 enp0s3
Macos 10.15
$ networksetup -listnetworkserviceorder
An asterisk (*) denotes that a network service is disabled.
(1) AX88179 USB 3.0 to Gigabit Ethernet
(Hardware Port: AX88179 USB 3.0 to Gigabit Ethernet, Device: en5)
(2) Wi-Fi
(Hardware Port: Wi-Fi, Device: en0)
(3) Bluetooth PAN
(Hardware Port: Bluetooth PAN, Device: en3)
(4) Thunderbolt Bridge
(Hardware Port: Thunderbolt Bridge, Device: bridge0)
(5) Corporate VPN
(Hardware Port: L2TP, Device: )
Windows 10
C:\Users\rj>route print
===========================================================================
Interface List
5...08 00 27 04 b9 fa ......Intel(R) PRO/1000 MT Desktop Adapter
3...02 00 4c 4f 4f 50 ......Npcap Loopback Adapter
1...........................Software Loopback Interface 1
===========================================================================
IPv4 Route Table
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 10.0.2.2 10.0.2.15 25
10.0.2.0 255.255.255.0 On-link 10.0.2.15 281
10.0.2.15 255.255.255.255 On-link 10.0.2.15 281
...
I have a dnsmasq server which I am using to serve DHCP and cache DNS. It is running on a Raspberry Pi. The range of addresses available in the pool is too small for the number of devices that regularly enter and leave the network, so I am trying to get it to serve addresses from a different subnet, but using the same gateway. but it is only allocating from one range.
There is lots of advice on how to allocate to different subnets based on which NIC is servicing the request or on mac address, but nothing on combining subnets in this way from a single NIC and having them use a single gateway. What is there suggests that the setup below should just work, but it just doesn't.
The man page is no help either.
Situation:
router/gateway: 192.168.1.1
DNS/DHCP: 192.168.1.2
reserved: 192.168.1.3-150
ON DNS Server:
/etc/network/interfaces
auto eth0
auto lo
iface lo inet loopback
iface eth0 inet static
address 192.168.1.2
gateway 192.168.1.1
netmask 255.255.0.0
network 192.168.0.0
broadcast 192.168.1.255
On DNS Server /etc/dnsmasq.conf
#/etc/dnsmasq.conf
domain-needed
bogus-priv
domain=local.net
expand-hosts
local=/local.net/
listen-address=192.168.1.2
bind-interfaces
cache-size=1000
dhcp-authoritative
dhcp-leasefile=/var/lib/dhcp/dhcpd.leases
dhcp-range=eth0,192.168.1.150,192.168.1.250,255.255.0.0,24h
dhcp-range=eth0,192.168.2.10,192.168.2.250,255.255.0.0,24h
dhcp-range=eth0,192.168.3.10,192.168.3.250,255.255.0.0,24h
dhcp-range=eth0,192.168.4.10,192.168.4.250,255.255.0.0,24h
dhcp-option=3,192.168.1.1
dhcp-option=6,192.168.1.2
dhcp-option=42,192.168.1.2
server=8.8.8.8
server=8.8.4.4
server=208.67.220.220
The solution above tries to set up 4 vlans:
dhcp-range=eth0,192.168.1.150,192.168.1.250,255.255.0.0,24h
dhcp-range=eth0,192.168.2.10,192.168.2.250,255.255.0.0,24h
dhcp-range=eth0,192.168.3.10,192.168.3.250,255.255.0.0,24h
dhcp-range=eth0,192.168.4.10,192.168.4.250,255.255.0.0,24h
But the answer is simply to increase the range in a single vlan (of course):
dhcp-range=eth0,192.168.1.150,192.168.4.250,255.255.0.0,24h
Folks,
I have a Ubuntu machine connected to the Internet through wireless (wlan0), and I am sharing this connection to my Ethernet port (eth1). Then, I have this Ethernet port connected to a switch, and two windows machine connected to the same switch. So the two windows machines have a static IP from the LAN generated from the route generated from wlan0 to eth1, so that I can communicate with all 3 computers at the same time (this works since I can ssh and remote access all 3 computers).
My problem is that I when I run my LCM program (with TTL = 1) on my windows PC, I cannot receive the messages on my Ubuntu machine (meaning that the message should pass through the Ethernet). How can I make sure the UDP messages can be routed back into my Ubuntu machine from the windows machines while the wireless network is running?
This was my solution to the problem (right there on the LCM website):
sudo ifconfig eth1 multicast
sudo route add -net 224.0.0.0 netmask 240.0.0.0 dev eth1
Now all my UDP packets are routed only through eth1. And my shared network (from wlan0) is still intact after this. So all computers have internet at the same time. So great!