randpkt [ -b <maxbytes> ] [ -c <count> ] [ -t <type> ] <filename>


randpkt is a small utility that creates a pcap trace file full of random packets.

By creating many randomized packets of a certain type, you can test packet sniffers to see how well they handle malformed packets. The sniffer can never trust the data that it sees in the packet because you can always sniff a very bad packet that conforms to no standard. randpkt produces very bad packets.

When creating packets of a certain type, randpkt uses a sample packet that is stored internally to randpkt. It uses this as the starting point for your random packets, and then adds extra random bytes to the end of this sample packet.

For example, if you choose to create random ARP packets, randpkt will create a packet which contains a predetermined Ethernet II header, with the Type field set to ARP. After the Ethernet II header, it will put a random number of bytes with random values.


-b <maxbytes>

Default 5000.

Defines the maximum number of bytes added to the sample packet. If you choose a maxbytes value that is less than the size of the sample packet, then your packets would contain only the sample packet…​ not much variance there! randpkt exits on that condition.

-c <count>

Default 1000.

Defines the number of packets to generate.

-t <type>

Default Ethernet II frame.

Defines the type of packet to generate:

arp             Address Resolution Protocol
bgp             Border Gateway Protocol
bvlc            BACnet Virtual Link Control
dns             Domain Name Service
eth             Ethernet
fddi            Fiber Distributed Data Interface
giop            General Inter-ORB Protocol
icmp            Internet Control Message Protocol
ip              Internet Protocol
ipv6            Internet Protocol Version 6
llc             Logical Link Control
m2m             WiMAX M2M Encapsulation Protocol
megaco          MEGACO
nbns            NetBIOS-over-TCP Name Service
ncp2222         NetWare Core Protocol
sctp            Stream Control Transmission Protocol
syslog          Syslog message
tds             TDS NetLib
tcp             Transmission Control Protocol
tr              Token-Ring
udp             User Datagram Protocol
usb             Universal Serial Bus
usb-linux       Universal Serial Bus with Linux specific header


--log-level <level>

Set the active log level. Supported levels in lowest to highest order are "noisy", "debug", "info", "message", "warning", "critical", and "error". Messages at each level and higher will be printed, for example "warning" prints "warning", "critical", and "error" messages and "noisy" prints all messages. Levels are case insensitive.

--log-fatal <level>

Abort the program if any messages are logged at the specified level or higher. For example, "warning" aborts on any "warning", "critical", or "error" messages.

--log-domains <list>

Only print messages for the specified log domains, e.g. "GUI,Epan,sshdump". List of domains must be comma-separated.

--log-debug <list>

Force the specified domains to log at the "debug" level. List of domains must be comma-separated.

--log-noisy <list>

Force the specified domains to log at the "noisy" level. List of domains must be comma-separated.

--log-file <path>

Write log messages and stderr output to the specified file.


To see a description of the randpkt options use:


To generate a capture file with 1000 DNS packets use:

randpkt -b 500 -t dns rand_dns.pcap

To generate a small capture file with just a single LLC frame use:

randpkt -b 100 -c 1 -t llc single_llc.pcap


pcap(3), editcap(1)