Rohan rohan-molloy

Cloud metadata

Many cloud providers such as Amazon AWS, Digitalocean and Vultr provide an instance metadata service.

Guest instances can discover their own parameters by accessing an API. By convention, this API is accessible from the address 169.254.169.254

To get the value of key 'k', we send an HTTP request to the relative location /$k If the key corresponds to a tuple, the request is rewritten to key/ which is an index. If no value or tuple exists, it simply returns not found

Using Nmap to troubleshoot DHCP

There are so many times where it's useful to take a peek at a DHCP enabled network, without actually having to apply any of the connection settings offered. You don't need an active ip address for this to work as DHCP uses broadcasts.

  $ sudo nmap --script broadcast-dhcp-discover --spoof-mac -n -e eth1 

  Starting Nmap 6.47 ( http://nmap.org ) at 2018-02-10 08:17 UTC
 Spoofing MAC address 00:01:BA:48:7C:24 (IC-Net)

Full backup using Busybox tar

The version of tar supplied with Busybox has a slightly different syntax to the more familiar GNU tar. Let's look at how we can use BusyBox tar to do a full system backup.

tar cv -C / -X /tmp/exclude.list -f /tmp/backup.tar .

Let's break these options down

cv
Tar is running in create mode, with verbosity enabled

Warning: this is intended for WAN hosts who don't usually have concurrent ssh connections

Step one Ensure that an entry for ssh-client.local exists in /etc/hosts:

echo "0.0.0.0 ssh-client.local" >>/etc/hosts

Step two

Add chain named "WIRELESS_PRE" in the "raw" table
This is equivalent to running iptables -t raw -N WIRELESS_PRE

firewall-cmd --permanent --direct --add-chain ipv4 raw WIRELESS_PRE

Insert a rule at position 1 of the above chain
This is equivalent to iptables -t raw -I WIRELESS_PRE

	SOCKSPort 9050
	TransPort 9040
	VirtualAddrNetworkIPv4 10.192.0.0/10
	AutomapHostsOnResolve 1
	DNSPort 5353


	sudo tar -cvpz
	--exclude=/proc \
	--exclude=/tmp \
	--exclude=/mnt \
	--exclude=/dev \
	--exclude=/sys \
	--exclude=/run \
	--exclude=/media \
	--exclude=/var/log \


	k=`for ((i=0; i != ${#key[@]}; i++)); do printf "\t\"${key[$i]}\":\""${value[$i]}"\",\n"; done`; echo "{"; echo "${k::-1}"; echo "}"