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ZMAP(1) zmap ZMAP(1) NAME zmap - The Fast Internet Scanner SYNOPSIS zmap [ -p <port(s)> ] [ -o <outfile> ] [ OPTIONS... ] [ ip/hostname/range ] DESCRIPTION ZMap is a network tool for scanning the entire IPv4 address space (or large samples). ZMap is capable of scanning the entire Internet in around 45 min- utes on a gigabit network connection, reaching ~98% theoretical line speed. OPTIONS BASIC OPTIONS ip/hostname/range IP addresses or DNS hostnames to scan. Accepts IP ranges in CIDR block notation. Defaults to 0.0.0/8 -p, --target-ports=port(s) List of TCP/UDP ports and/or port ranges to scan (e.g., 80,443,100-105). Use '*' to scan all ports, including port 0. -o, --output-file=name When using an output module that uses a file, write results to this file. Use - for stdout. -b, --blocklist-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 blocklist file blocklist.conf for this purpose. -w, --allowlist-file=path File of subnets to scan, in CIDR notation, one-per line. Specifying a allowlist file is equivalent to specifying to ranges directly on the command line interface, but allows specifying a large number of subnets. Note: if you are specifying a large number of individual IP addresses (more than 10 million), you should instead use --list-of-ips-file. -I, --list-of-ips-file=path File of individual IP addresses to scan, one-per line. This feature allows you to scan a large number of unrelated addresses. If you have a small number of IPs, it is faster to specify these on the command line or by using --allowlist-file. This should only be used when scanning more than 10 million addresses. When used in with --allowlist-path, only hosts in the intersection of both sets will be scanned. Hosts specified here, but included in the blocklist will be excluded. SCAN OPTIONS -r, --rate=pps Set the send rate in packets/sec. Note: when combined with --probes, this is total packets per second, not IPs per second. Setting the rate to 0 will scan at full line rate. Default: 10000 pps. -B, --bandwidth=bps Set the send rate in bits/second (supports suffixes G, M, and K (e.g. -B 10M for 10 mbps). This overrides the --rate flag. -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 ad- dress space (after excluding blocklist). A target is an IP/port pair, if scanning multiple ports, and an IP otherwise. In the case of percents and multiple ports, the percent is of the total number of IP/port pair combinations. -N, --max-results=n Exit after receiving this many results -t, --max-runtime=secs Cap the length of time for sending packets -c, --cooldown-time=secs How long to continue receiving after sending has completed (de- fault=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. -P, --probes=n Number of probes to send to each IP/Port pair (default=1). Probes are sent sequentially for a given IP/Port, so if --probes=4, we'll send 4 probe packets sequentially to that target rather than iterat- ing across the target space 4 times. Since ZMap composes Ethernet frames directly, probes can be lost en-route to destination. In- creasing the --probes increases the chance that an online host will receive a probe in an unreliable network. This is contrasted with --retries which just gives the number of attempts to send a single probe on the source NIC. --retries=n Number of times to try resending a packet if the sendto call fails (default=10) --batch=n Number of packets to batch before calling the appropriate syscall to send. Used to take advantage of Linux's sendmmsg syscall to send the entire batch at once. Only available on Linux, other OS's will send each packet individually. (default=64) SCAN SHARDING --shards=N Split the scan up into N shards/partitions among different instances of zmap (default=1). When sharding, --seed is required. --shard=n 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. NETWORK OPTIONS -s, --source-port=port|range Source port(s) to send packets from --validate-source-port=enable|disable Used as an override to enable/disable source port validation. Source port validation will check that a received probe response's src port matches the dst port of the probe sent to that IP/port pair. This ensures that multiple ZMap scans to the same hosts but to different ports will not interfere with each other. This overrides each mod- ules default behavior on whether or not to validate source ports with probe responses. -S, --source-ip=ip|range Source address(es) to send packets from. Either single IP or range (e.g. 10.0.0.1-10.0.0.9) -G, --gateway-mac=addr Gateway MAC address to send packets to (in case auto-detection fails) --source-mac=addr Source MAC address to send packets from (in case auto-detection fails) -i, --interface=name Network interface to use -X, --iplayer Send IP layer packets instead of ethernet packets (for non-Ethernet interface) --netmap-wait-ping=ip (Netmap only) Wait for ip to respond to ICMP Echo request before commencing scan. Useful if connected to a switch with STP enabled, where the PHY reset that is needed for entering and leaving Netmap mode will cause the switch to mute the port until the spanning tree protocol has determined that the link should be set into forward state. PROBE OPTIONS ZMap allows users to specify and write their own probe modules. Probe mod- ules are responsible for generating probe packets to send, and processing responses from hosts. --list-probe-modules List available probe modules (e.g. tcp_synscan) -M, --probe-module=name Select probe module (default=tcp_synscan) --probe-args=args Arguments to pass to probe module --probe-ttl=hops Set TTL value for probe IP packets --list-output-fields 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 re- turned by the probe module, and outputting them to the user. Users can specify output fields, and write filters over the output fields. --list-output-modules List available output modules (e.g. csv) -O, --output-module=name Select output module (default=csv) --output-args=args Arguments to pass to output module -f, --output-fields=fields Comma-separated list of fields to output --output-filter Specify an output filter over the fields defined by the probe mod- ule. See the output filter section for more details. --no-header-row Excludes any header rows (e.g., CSV header fields) from ZMap output. This is useful if you're piping results into another application that expects only data. RESPONSE DEDUPLICATION Hosts will oftentimes send multiple responses to a probe (either because the scanner doesn't send back a RST packet or because the host has a misim- plemented TCP stack. To address this, ZMap will attempt to deduplicate re- sponsive (ip,port) targets. --dedup-method Specifies the method ZMap will use to deduplicate responses. Options are: full, window, and none. Full deduplication uses a 32-bit bitmap and guarantees that no duplicates will be emitted. However, full-deduplication requires around 500MB of memory for a single port. We do not support full deduplication for multiple ports. Win- dow uses a sliding window of the last (user-defined) number of re- sponses as set by --dedup-window-size. None will prevent any dedu- plication. --dedup-window-size=targets Specifies the size of the sliding window as the last n target re- sponses to be used for deduplication. Only applicable if using win- dow deduplication. LOGGING AND METADATA OPTIONS -q, --quiet Do not print status updates once per second -v, --verbosity=n Level of log detail (0-5, default=3) -l, --log-file=filename Output file for log messages. By default, stderr. -m, --metadata-file=filename Output file for scan metadata (JSON) -L, --log-directory Write log entries to a timestamped file in this directory -u, --status-updates-file Write scan progress updates to CSV file" --disable-syslog Disables logging messages to syslog --notes Inject user-specified notes into scan metadata --user-metadata Inject user-specified JSON metadata into scan metadata ADDITIONAL OPTIONS -T, --sender-threads=n Threads used to send packets. ZMap will attempt to detect the opti- mal number of send threads based on the number of processor cores. Defaults to min(4, number of processor cores on host - 1). -C, --config=filename Read a configuration file, which can specify any other options. -d, --dryrun Print out each packet to stdout instead of sending it (useful for debugging) --fast-dryrun Don't actually send packets, print out a binary representation probe dst IP and dst Port. Used for faster integration tests, not for gen- eral use. --max-sendto-failures Maximum NIC sendto failures before scan is aborted --min-hitrate Minimum hitrate that scan can hit before scan is aborted --cores Comma-separated list of cores to pin to --ignore-blocklist-errors Ignore invalid, malformed, or unresolvable entries in al- lowlist/blocklist file. Replaces the pre-v3.x --ignore-invalid-hosts option. -h, --help Print help and exit -V, --version Print version and exit OUTPUT 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 suc- cessful 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 expres- sions 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" UDP PROBE MODULE OPTIONS These arguments are all passed using the --probe-args=args option. Only one argument may be passed at a time. file:/path/to/file Path to payload file to send to each host over UDP. template:/path/to/template Path to template file. For each destination host, the template file is populated, set as the UDP payload, and sent. text:<text> ASCII text to send to each destination host hex:<hex> Hex-encoded binary to send to each destination host template-fields Print information about the allowed template fields and exit. MID-SCAN CHANGES You can change the rate at which ZMap is scanning mid-scan by sending SI- GUSR1 (increase) and SIGUSR2 (decrease) signals to ZMap. These will result in the scan rate increasing or decreasing by 5%. ZMap November 2025 ZMAP(1)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS
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