I want to assign a static IP address in Ubuntu using eth0 port. But when I run ifconfig, eth0 is not there:
How will I assign a static address to eth0?
Related
I dont understand the ARP table of 1 machine on my testing network consisting of 3 PCs on Ubuntu20
a client of IP 192.168.0.1
an attacker of IP 192.168.0.2
a server of IP 192.168.0.3
On machine n°2 (attacker), I've installed :
dnsiff and launched arpspoof ( sudo arpspoof -t 192.168.0.1 192.168.0.3)
mitmproxy in transparent mode, which makes a proxy and redirects all the traffic arriving on port 80 to port 8080 by setting properly the iptables rules.
sudo apt install dnsiff
sudo apt install mitmproxy
I activated the ip_forwarding by uncommenting net.ipv4.ip_forward=1 in file /etc/sysctl.conf and then reloaded the system :
sudo sysctl -p /etc/sysctl.conf
mitmproxy --mode-transparent -p 8080
sudo iptables -t nat -A PREROUTING -p tcp --destination-port 80 -j REDIRECT --to-port 8080
All works but when I open the arp table of machine 1 (192.168.0.1) , I read :
192.168.0.3 #MAC of the attacker (which is what I expected)
192.168.0.2 #MAC of the attacker (which is surprinsing)
How is it that address 192.168.0.2 appears whereas there is no trace on any wireshark frame , when wireshark listens to machine 1 interface.
Another surprinsing thing occurs when I set manually the #IP et #MAC of the server :
sudo arp -s 192.168.0.3 #MAC of the attacker
This time the ARP table of machine 1 does not display 192.168.0.2 (attacker).
Thank you for any explanation.
I have read the documentation and I know that:
To enable a real can you do
$ sudo ip link set can0 type can bitrate 125000
$ sudo ip link set up can0
and to enable a vcan you do
$ modprobe vcan
$ sudo ip link add dev vcan0 type vcan
$ sudo ip link set up vcan0
In my case, I even disable vcan before enabling can as in
$ sudo ip link set dev vacn0 down
$ sudo ip link set can0 type can bitrate 125000
$ sudo ip link set up can0
My question is how about the opposite? (Going from can to vcan)?
If my can is up , should I disable it before enabling vcan? and how?
and also enabling vcan uses add not set... why?
There is no connection between real CAN network devices and virtual CAN devices, other than they share the same socket interface.
What you've shown here is how you make either kind of CAN device (real or virtual) active and set it up.
How you'd switch between one and the other in your application should be as simple as using one or the other name for the network device.
You can have real CAN and virtual CAN devices available and up at the same time with no concerns.
As for why you need to add your vcan0 device but not to add your real can0 device, the operating system usually detects your CAN hardware and creates the device automatically.
One exception to this is if you're using a CAN-to-serial adapter with slcand, where you would need to run slcand first (and it will create devices named like slcan0):
$ sudo slcand -o -s8 -t hw -S 3000000 /dev/ttyUSB0
$ sudo ip link set up slcan0
I need to run wireguard only for a single program, and have the rest of my system not use it. Is this possible or doable? I'm currently using wg-quick
Yes you can, using network namespaces.
First let's create the wireguard namespace:
ip netns add wireguard
Then, we create a wireguard interface in your standard namespace
ip link add wg0 type wireguard
(You can configure the interface here)
We move it to the wireguard namespace
ip link set wg0 netns wireguard
And now, you can run a process in the wireguard namespace using
sudo -E ip netns exec wireguard sudo -E -u \#$(id -u) -g \#$(id -g) YOUR_PROCESS_CMD
You should read this for more information: https://www.wireguard.com/netns
i have got a new Linux Server (Debian 6.0) with a Database (MySQL) which is accessed by Port 3306 like as usual.
Now I'd like to access the database due port problems of some users (because port 3306 is often blocked by network firewalls) by port 80 or 443. So the transfer must be redirected from Port 80 to 3306 to keep the Database working.
I have tried following command:
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3306
but I got following error:
iptables: No chain/target/match by that name.
Does anyone can help me solve this problem? The NAT table is empty (PREROUTING,POSTROUTING,OUTPUT have no entries) (checked with iptables -t nat -n -L)
In iptables Kernel modules required for NAT functionality:
Run following command to load modules in kernel:
# modprobe iptable_nat
# modprobe ipt_REDIRECT
Make sure you have above modules compiled in kernel:
[root#instructor tmp]# grep REDIRECT /boot/config-$( uname -r )
CONFIG_IP_NF_TARGET_REDIRECT=m
CONFIG_BRIDGE_EBT_REDIRECT=m
In VPS Server:
Enable modules on host server using modprobe command
Execute following command from the host server to enable all the modules for the VPS
vzctl set VEID --iptables iptable_nat --iptables ipt_REDIRECT
Add rules in file /etc/vz/conf/veid.conf
IPTABLES="iptable_nat ipt_REDIRECT"
i want to check if the LAN cable is plugged in on a linux system, is there any file in /sys or /proc that i can check (i would like to do it in C)?
To check if a cable is plugged you can look in /sys/class/net/
For ex. for eth0 connection:
$ grep "" /sys/class/net/eth0/*
/sys/class/net/eth0/carrier:0
/sys/class/net/eth0/operstate:down
As you can see, cable isn't plugged.
if it was plugged i was getting:
/sys/class/net/eth0/carrier:1
/sys/class/net/eth0/operstate:up
Run the ifconfig command which will show all the interfaces connected.