Nothing else than what the title says. Simple PowerShell script for dumping the IP address:
wsl -- ip -o -4 -json addr list eth0 ` | ConvertFrom-Json ` | %{ $_.addr_info.local } ` | ?{ $_ }
Assume that we have a service only available in localhost (127.0.0.1/8) and we want to expose this port temporarily. Of course, you can use iptables for redirecting the port. But take care, this is not a simple DNAT because packets will not be evaluated by PREROUTING (-t nat) rules.
Another option is using an old-powerful Swiss knife tool: socat (github) (my fork).
# binds public port to any local interface socat TCP-LISTEN:<public_port>,fork TCP:127.0.0.1:<internal_port> # binds only to an IP address SOCAT_SOCKADDR=<interface_IP> socat TCP-LISTEN:<public_port>,fork TCP:127.0.0.1:<internal_port> # examples: # binds to all interfaces: socat TCP-LISTEN:1880,fork TCP:127.0.0.1:1880 # just for an IP address of one interface: SOCAT_SOCKADDR=10.2.0.110 socat TCP-LISTEN:1880,fork TCP:127.0.0.1:1880
I was afraid for missing my files, configurations and much other staff that I had in Linux filesystem of WSL2 (Windows 10). But I had to upgrade because of compatibility with an application that I need. So, finally, I decided to upgrade the Ubuntu 18.04 that I installed in WSL2 to a newer version 20.04. Yes, I know that there is 22.04 available nowadays, but I wasn’t comfortable jumping to many versions.
I followed simple steps that I found at:
How To Upgrade Existing WSL/WSL2 Ubuntu 18.04 to 20.04
The steps in a nutshell were:
sudo apt update sudo apt upgrade -y sudo apt --purge autoremove sudo apt install update-manager-core sudo do-release-upgrade
When I answered all the questions and after stopping the WSL2 VM with:
# command that I ran from 'cmd.exe' (Windows console) wsl --shutdown
I had and issue rebooting, WSL2 didn’t boot and it gave this message:
wsl/usr/sbin/enter-systemd-namespace: line 10: /usr/sbin/daemonize: No such file or directoryI resolved the problem, shutting down the WSL and running the command:
wsl -u root -e bash --noprofile --norcIt gave me a root console where I could modify the file:
/usr/sbin/enter-systemd-namespace
specifically, in line 10, I changed:
/usr/sbin/daemonize
to
/usr/bin/daemonize
And when I accessed to WSL2 everything worked perfectly. I used to access WSL2 from Windows Terminal which uses the command:
C:\WINDOWS\system32\wsl.exe -d Ubuntu-18.04But it has small issues with bybou, finally I changed this command to:
C:\WINDOWS\system32\bash.exe ~ -loginI love to use a console with byobu enabled when access the shell, but with my former command, the command ‘byobu-enable’ was ignored. I didn’t find why, in the end the solution was to change the command that I use for accessing Linux console (WSL2).
Likewise, I hope these notes can help someone.
When you are playing with Windows Hyper-V and you want to create a completely virtual internal network with private virtual machines inside your Windows 10 machine virtual switch are mandatory.
Then it’s the time to connect that virtual switch with the host machine using a virtual network interface. All those steps can be done using Hyper-V manager user interface, but you cannot control 100% of parameters like enable, or not, the NAT of the virtual internal network.
Using PowerShell the steps are:
New-VMSwitch -SwitchName NATSwitch -SwitchType Internal New-NetIPAddress -IPAddress 10.46.1.1 -PrefixLength 24 -InterfaceAlias "vEthernet (NATSwitch)" New-NetNAT -Name NATNetwork -InternalIPInterfaceAddressPrefix 10.46.1.0/24
Of course, change “NATSwitch” for your switch name and “10.46.1.1” for the IP address of the host virtual network card. Finally “NATNetwork” is another arbitrary name for referring to the NAT rule, and “10.46.1.0/24” is the network address of the virtual internal host network.
Running the commands looks like:
For removing what you did:
Remove-VMSwitch -Name "NATSwitch" Remove-NetIPAddress -InterfaceAlias "vEthernet (NATSwitch)" Remove-NetNAT -Name NATNetwork
In Windows 10 IP forwarding is not enabled and packets between interfaces are not routed. According to the Microsoft forums, you can enable IP forwarding (routing) using the following steps:
Go to Start and search on cmd or command. Right click on either cmd or command then select Run as administrator. At the command prompt type regedit. Navigate to the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ Services\Tcpip\Parameters\IPEnableRouter setting, right click and select Modify. Change 0 to 1 and exit the editor.
When your back at the command prompt type services.msc and navigate to the Routing and Remote Access service. Right click and select Properties. Change to Automatic and click on Start to start the service.
I had to research a long time until I found all this information, but in my case leverage my proofs of concepts to another level.
It’s just an IP spoofing protection which is by default enabled on Linux kernels. When it’s value is ‘1’ means that all IP address which are not directly routable and received form a network interface they are directly discarded.
So, if you want to scan a range of IP address in your LAN which not belong to that interface address space when packets from IP addresses are received they are going to be discarded by the kernel. So, take that into account when you have those “unusual” requirements.
It can be enable/disabled by all interfaces or just one:
root@mini9:/proc/sys/net/ipv4# cat ./conf/all/rp_filter 1 root@mini9:/proc/sys/net/ipv4# cat ./conf/ztly5q4n37/rp_filter 1
No words just a simple an powerful .ps1 script:
while (1) { Start-Process -NoNewWindow -FilePath 'C:\ProgramData\ZeroTier\One\zerotier-one_x64.exe' -ArgumentList "-q","peers"; sleep 5; cls }Or just a command, even equally useful.
When you want to discover LAN metadata without being part of that network. So, when you want to discover network address range, gateway, DNS IPs, DHCP server IPs, etc. this simple nmap parameter will help you so much.
# nmap --script broadcast-dhcp-discover Starting Nmap 7.60 ( https://nmap.org ) at 2021-05-19 15:07 CEST Pre-scan script results: | broadcast-dhcp-discover: | Response 1 of 1: | IP Offered: 192.168.1.127 | DHCP Message Type: DHCPOFFER | Subnet Mask: 255.255.255.0 | Renewal Time Value: 4d00h00m00s | Rebinding Time Value: 7d00h00m00s | IP Address Lease Time: 8d00h00m00s | Server Identifier: 192.168.1.1 | Router: 192.168.1.1 |_ Domain Name Server: 8.8.8.8, 8.8.4.4 WARNING: No targets were specified, so 0 hosts scanned. Nmap done: 0 IP addresses (0 hosts up) scanned in 1.43 seconds
Simple shell script based on bash which monitor a host with command line ping. Just bash and ping are the unique dependencies. Only state change are going to be printed:
#!/bin/bash IP="THE_IP_TO_MONITOR" STATE="offline" show_state() { echo "$(date '+%Y-%m-%dT%H:%M:%S') - " + $STATE; } while true; do ping -c 4 $IP > /dev/null 2>&1 if [ "$?" = "0" ]; then if [ "$STATE" = "offline" ]; then STATE="online" show_state fi else if [ "$STATE" = "online" ]; then STATE="offline" show_state fi fi sleep 10 done
# pre-installed on Ubuntu 18: tracepath -n IP/HOST mtr -n IP/HOST
When you work with embedded systems sometimes you would feel happy to have a Linux box until you discover there are plenty of basic things that you don’t have available, the extreme of that could be the ‘ps’ command which is used most of the time for checking if any process is running . Maybe you know that thanks the /proc filesystem there is access to the source of the information.
Keep next command close for solving this inconvenience he next time:
find /proc -mindepth 2 -maxdepth 2 -name exe -exec ls -lh {} \; 2>/dev/null