robertdavidgraham/masscanTCP port scanner, spews SYN packets asynchronously, scanning entire Internet in under 5 minutes.
This is an Internet-scale port scanner. It can scan the entire Internet in under 5 minutes, transmitting 10 million packets per second, from a single machine.
Its usage (parameters, output) is similar to nmap, the most famous port scanner.
When in doubt, try one of those features -- features that support widespread
scanning of many machines are supported, while in-depth scanning of single
machines aren't.
Internally, it uses asynchronous transmission, similar to port scanners
like scanrand, unicornscan, and ZMap. It's more flexible, allowing
arbitrary port and address ranges.
NOTE: masscan uses its own ad hoc TCP/IP stack. Anything other than
simple port scans may cause conflict with the local TCP/IP stack. This means you
need to use either the --src-ip option to run from a different IP address, or
use --src-port to configure which source ports masscan uses, then also
configure the internal firewall (like pf or iptables) to firewall those ports
from the rest of the operating system.
This tool is free, but consider contributing money to its development: Bitcoin wallet address: 1MASSCANaHUiyTtR3bJ2sLGuMw5kDBaj4T
On Debian/Ubuntu, it goes something like the following. It doesn't
really have any dependencies other than a C compiler (such as gcc
or clang).
sudo apt-get --assume-yes install git make gcc
git clone https://github.com/robertdavidgraham/masscan
cd masscan
make
This puts the program in the masscan/bin subdirectory.
To install it (on Linux) run:
make install
The source consists of a lot of small files, so building goes a lot faster
by using the multi-threaded build. This requires more than 2gigs on a
Raspberry Pi (and breaks), so you might use a smaller number, like -j4 rather than
all possible threads.
make -j
While Linux is the primary target platform, the code runs well on many other systems (Windows, macOS, etc.). Here's some additional build info:
makemakegmakecc src/*.c -o bin/masscanOn macOS, the x86 binaries seem to work just as fast under ARM emulation.
Usage is similar to nmap. To scan a network segment for some ports:
# masscan -p80,8000-8100 10.0.0.0/8 2603:3001:2d00:da00::/112
This will:
10.x.x.x subnet, and 2603:3001:2d00:da00::x subnets<stdout> that can be redirected to a fileTo see the complete list of options, use the --echo feature. This
dumps the current configuration and exits. This output can be used as input back
into the program:
# masscan -p80,8000-8100 10.0.0.0/8 2603:3001:2d00:da00::/112 --echo > xxx.conf
# masscan -c xxx.conf --rate 1000
Masscan can do more than just detect whether ports are open. It can also complete the TCP connection and interaction with the application at that port in order to grab simple "banner" information.
Masscan supports banner checking on the following protocols:
The problem with this is that masscan contains its own TCP/IP stack separate from the system you run it on. When the local system receives a SYN-ACK from the probed target, it responds with a RST packet that kills the connection before masscan can grab the banner.
The easiest way to prevent this is to assign masscan a separate IP address. This would look like one of the following examples:
# masscan 10.0.0.0/8 -p80 --banners --source-ip 192.168.1.200
# masscan 2a00:1450:4007:810::/112 -p80 --banners --source-ip 2603:3001:2d00:da00:91d7:b54:b498:859d
The address you choose has to be on the local subnet and not otherwise be used by another system. Masscan will warn you that you've made a mistake, but you might've messed up the other machine's communications for several minutes, so be careful.
In some cases, such as WiFi, this isn't possible. In those cases, you can firewall the port that masscan uses. This prevents the local TCP/IP stack from seeing the packet, but masscan still sees it since it bypasses the local stack. For Linux, this would look like:
# iptables -A INPUT -p tcp --dport 61000 -j DROP
# masscan 10.0.0.0/8 -p80 --banners --source-port 61000
You probably want to pick ports that don't conflict with ports Linux might otherwise choose for source-ports. You can see the range Linux uses, and reconfigure that range, by looking in the file:
/proc/sys/net/ipv4/ip_local_port_range
On the latest version of Kali Linux (2018-August), that range is 32768 to 60999, so you should choose ports either below 32768 or 61000 and above.
Setting an iptables rule only lasts until the next reboot. You need to lookup how to
save the configuration depending upon your distro, such as using iptables-save
and/or iptables-persistent.
On Mac OS X and BSD, there are similar steps. To find out the ranges to avoid, use a command like the following:
# sysctl net.inet.ip.portrange.first net.inet.ip.portrange.last
On FreeBSD and older MacOS, use an ipfw command:
# sudo ipfw add 1 deny tcp from any to any 40000 in
# masscan 10.0.0.0/8 -p80 --banners --source-port 40000
On newer MacOS and OpenBSD, use the pf packet-filter utility.
Edit the file /etc/pf.conf to add a line like the following:
block in proto tcp from any to any port 40000:40015
Then to enable the firewall, run the command:
# pfctl -E
If the firewall is already running, then either reboot or reload the rules with the following command:
# pfctl -f /etc/pf.conf
Windows doesn't respond with RST packets, so neither of these techniques are necessary. However, masscan is still designed to work best using its own IP address, so you should run that way when possible, even when it is not strictly necessary.
The same thing is needed for other checks, such as the --heartbleed check,
which is just a form of banner checking.
While useful for smaller, internal networks, the program is really designed with the entire Internet in mind. It might look something like this:
# masscan 0.0.0.0/0 -p0-65535
Scanning the entire Internet is bad. For one thing, parts of the Internet react badly to being scanned. For another thing, some sites track scans and add you to a ban list, which will get you firewalled from useful parts of the Internet. Therefore, you want to exclude a lot of ranges. To blacklist or exclude ranges, you want to use the following syntax:
# masscan 0.0.0.0/0 -p0-65535 --excludefile exclude.txt
This just prints the results to the command-line. You probably want them saved to a file instead. Therefore, you want something like:
# masscan 0.0.0.0/0 -p0-65535 -oX scan.xml
This saves the results in an XML file, allowing you to easily dump the results in a database or something.
But, this only goes at the default rate of 100 packets/second, which will take forever to scan the Internet. You need to speed it up as so:
# masscan 0.0.0.0/0 -p0-65535 --max-rate 100000
This increases the rate to 100,000 packets/second, which will scan the entire Internet (minus excludes) in about 10 hours per port (or 655,360 hours if scanning all ports).