zmap - Man Page

The Fast Internet Scanner


zmap [ -p <port> ] [ -o <outfile> ] [ Options... ] [ ip/hostname/range ]


ZMap is a network tool for scanning the entire Internet (or large samples). ZMap is capable of scanning the entire Internet in around 45 minutes on a gigabit network connection, reaching ~98% theoretical line speed.


Basic Options


IP addresses or DNS hostnames to scan. Accepts IP ranges in CIDR block notation. Defaults to 0.0.0/8

-p, --target-port=port

TCP or UDP port number to scan (for SYN scans and basic UDP scans)

-o, --output-file=name

When using an output module that uses a file, write results to this file. Use - for stdout.

-b, --blacklist-file=path

File of subnets to exclude, in CIDR notation, one-per line. It is recommended you use this to exclude RFC 1918 addresses, multicast, IANA reserved space, and other IANA special-purpose addresses. An example blacklist file blacklist.conf for this purpose.

Scan Options

-n, --max-targets=n

Cap the number of targets to probe. This can either be a number (e.g. -n 1000) or a percentage (e.g. -n 0.1%) of the scannable address space (after excluding blacklist)

-N, --max-results=n

Exit after receiving this many results

-t, --max-runtime=secs

Cap the length of time for sending packets

-r, --rate=pps

Set the send rate in packets/sec

-B, --bandwidth=bps

Set the send rate in bits/second (supports suffixes G, M, and K (e.g. -B 10M for 10 mbps). Thi s overrides the --rate flag.

-c, --cooldown-time=secs

How long to continue receiving after sending has completed (default=8)

-e, --seed=n

Seed used to select address permutation. Use this if you want to scan addresses in the same order for multiple ZMap runs.


Split the scan up into N shards/partitions among different instances of zmap (default=1). When sharding, --seed is required.


Set which shard to scan (default=0). Shards are 0-indexed in the range [0, N), where N is the total number of shards. When sharding --seed is required.

-T, --sender-threads=n

Threads used to send packets. ZMap will attempt to detect the optimal number of send threads based on the number of processor cores.

-P, --probes=n

Number of probes to send to each IP (default=1)

-d,  --dryrun

Print out each packet to stdout instead of sending it (useful for debugging)

Network Options

-s, --source-port=port|range

Source port(s) to send packets from

-S, --source-ip=ip|range

Source address(es) to send packets from. Either single IP or range (e.g.

-G, --gateway-mac=addr

Gateway MAC address to send packets to (in case auto-detection does not work)

-i, --interface=name

Network interface to use

Probe Options

ZMap allows users to specify and write their own probe modules. Probe modules are responsible for generating probe packets to send, and processing responses from hosts.


List available probe modules (e.g. tcp_synscan)

-M, --probe-module=name

Select probe module (default=tcp_synscan)


Arguments to pass to probe module


List the fields the selected probe module can send to the output module

Output Options

ZMap allows users to specify and write their own output modules for use with ZMap. Output modules are responsible for processing the fieldsets returned by the probe module, and outputing them to the user. Users can specify output fields, and write filters over the output fields.


List available output modules (e.g. tcp_synscan)

-O, --output-module=name

Select output module (default=csv)


Arguments to pass to output module

-f, --output-fields=fields

Comma-separated list of fields to output


Specify an output filter over the fields defined by the probe module. See the output filter section for more details.

Additional Options

-C, --config=filename

Read a configuration file, which can specify any other options.

-q,  --quiet

Do not print status updates once per second

-g,  --summary

Print configuration and summary of results at the end of the scan

-v, --verbosity=n

Level of log detail (0-5, default=3)

-h,  --help

Print help and exit

-V,  --version

Print version and exit

UDP Probe Module Options

These arguments are all passed using the --probe-args=args option. Only one argument may be passed at a time.


Path to payload file to send to each host over UDP.


Path to template file. For each destination host, the template file is populated, set as the UDP payload, and sent.


ASCII text to send to each destination host


Hex-encoded binary to send to each destination host


Print information about the allowed template fields and exit.

Ouput Filters

Results generated by a probe module can be filtered before being passed to the output module. Filters are defined over the output fields of a probe module. Filters are written in a simple filtering language, similar to SQL, and are passed to ZMap using the --output-filter option. Output filters are commonly used to filter out duplicate results, or to only pass only sucessful responses to the output module.

Filter expressions are of the form <fieldname> <operation> <value>. The type of <value> must be either a string or unsigned integer literal, and match the type of <fieldname>. The valid operations for integer comparisons are = !=, ,, =,=. The operations for string comparisons are =, !=. The --list-output-fields flag will print what fields and types are available for the selected probe module, and then exit.

Compound filter expressions may be constructed by combining filter expressions using parenthesis to specify order of operations, the && (logical AND) and || (logical OR) operators.

For example, a filter for only successful, non-duplicate responses would be written as: --output-filter="success = 1 && repeat = 0"


September 2015 zmap v2.1.1