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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SYNTAX | USAGE EXAMPLE | NOTE | BUGS | LEGAL | HISTORY | SEE ALSO | AUTHOR | COLOPHON | COLOPHON |
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TRAFGEN(8) netsniff-ng toolkit TRAFGEN(8)
trafgen - a fast, multithreaded network packet generator
trafgen [options] [packet]
trafgen is a fast, zero-copy network traffic generator for
debugging, performance evaluation, and fuzz-testing. trafgen
utilizes the packet(7) socket interface of Linux which postpones
complete control over packet data and packet headers into the
user space. It has a powerful packet configuration language,
which is rather low-level and not limited to particular
protocols. Thus, trafgen can be used for many purposes. Its only
limitation is that it cannot mimic full streams resp. sessions.
However, it is very useful for various kinds of load testing in
order to analyze and subsequently improve systems behaviour under
DoS attack scenarios, for instance.
trafgen is Linux specific, meaning there is no support for other
operating systems, same as netsniff-ng(8), thus we can keep the
code footprint quite minimal and to the point. trafgen makes use
of packet(7) socket's TX_RING interface of the Linux kernel,
which is a mmap(2)'ed ring buffer shared between user and kernel
space.
By default, trafgen starts as many processes as available CPUs,
pins each of them to their respective CPU and sets up the ring
buffer each in their own process space after having compiled a
list of packets to transmit. Thus, this is likely the fastest one
can get out of the box in terms of transmission performance from
user space, without having to load unsupported or non-mainline
third-party kernel modules. On Gigabit Ethernet, trafgen has a
comparable performance to pktgen, the built-in Linux kernel
traffic generator, except that trafgen is more flexible in terms
of packet configuration possibilities. On 10-Gigabit-per-second
Ethernet, trafgen might be slower than pktgen due to the
user/kernel space overhead but still has a fairly high
performance for out of the box kernels.
trafgen has the potential to do fuzz testing, meaning a packet
configuration can be built with random numbers on all or certain
packet offsets that are freshly generated each time a packet is
sent out. With a built-in IPv4 ping, trafgen can send out an ICMP
probe after each packet injection to the remote host in order to
test if it is still responsive/alive. Assuming there is no answer
from the remote host after a certain threshold of probes, the
machine is considered dead and the last sent packet is printed
together with the random seed that was used by trafgen. You might
not really get lucky fuzz-testing the Linux kernel, but
presumably there are buggy closed-source embedded systems or
network driver's firmware files that are prone to bugs, where
trafgen could help in finding them.
trafgen's configuration language is quite powerful, also due to
the fact, that it supports C preprocessor macros. A stddef.h is
being shipped with trafgen for this purpose, so that well known
defines from Linux kernel or network programming can be reused.
After a configuration file has passed the C preprocessor stage,
it is processed by the trafgen packet compiler. The language
itself supports a couple of features that are useful when
assembling packets, such as built-in runtime checksum support for
IP, UDP and TCP. Also it has an expression evaluator where
arithmetic (basic operations, bit operations, bit shifting, ...)
on constant expressions is being reduced to a single constant on
compile time. Other features are ''fill'' macros, where a packet
can be filled with n bytes by a constant, a compile-time random
number or run-time random number (as mentioned with fuzz
testing). Also, netsniff-ng(8) is able to convert a pcap file
into a trafgen configuration file, thus such a configuration can
be further tweaked for a given scenario.
-i <cfg|pcap|->, -c <cfg|->, --in <cfg|pcap|->, --conf <cfg|->
Defines the input configuration file that can either be
passed as a normal plain text file or via stdin (''-'').
Note that currently, if a configuration is passed through
stdin, only 1 CPU will be used. It is also possible to
specify PCAP file with .pcap extension via -i/--in option,
by default packets will be sent at rate considering
timestamp from PCAP file which might be reset via the -b
or -t option.
-o <dev|.pcap|.cfg>, -d <dev|.pcap|.cfg>, --out <dev|.pcap|.cfg>,
--dev <dev|.pcap|.cfg>
Defines the outgoing networking device such as eth0, wlan0
and others or a *.pcap or *.cfg file. Pcap and
configuration files are identified by extension.
-p, --cpp
Pass the packet configuration to the C preprocessor before
reading it into trafgen. This allows #define and #include
directives (e.g. to include definitions from system
headers) to be used in the trafgen configuration file.
-D <name>=<definition>, --define <name>=<definition>
Add macro definition for the C preprocessor to use it
within trafgen file. This option is used in combination
with the -p/--cpp option.
-J, --jumbo-support
By default trafgen's ring buffer frames are of a fixed
size of 2048 bytes. This means that if you're expecting
jumbo frames or even super jumbo frames to pass your line,
then you will need to enable support for that with the
help of this option. However, this has the disadvantage of
a performance regression and a bigger memory footprint for
the ring buffer.
-R, --rfraw
In case the output networking device is a wireless device,
it is possible with trafgen to turn this into monitor mode
and create a mon<X> device that trafgen will be
transmitting on instead of wlan<X>, for instance. This
enables trafgen to inject raw 802.11 frames. In case if
the output is a pcap file the link type is set to 127
(ieee80211 radio tap).
-s <ipv4>, --smoke-test <ipv4>
In case this option is enabled, trafgen will perform a
smoke test. In other words, it will probe the remote end,
specified by an <ipv4> address, that is being ''attacked''
with trafgen network traffic, if it is still alive and
responsive. That means, after each transmitted packet that
has been configured, trafgen sends out ICMP echo requests
and waits for an answer before it continues. In case the
remote end stays unresponsive, trafgen assumes that the
machine has crashed and will print out the content of the
last packet as a trafgen packet configuration and the
random seed that has been used in order to reproduce a
possible bug. This might be useful when testing
proprietary embedded devices. It is recommended to have a
direct link between the host running trafgen and the host
being attacked by trafgen.
-n <0|uint>, --num <0|uint>
Process a number of packets and then exit. If the number
of packets is 0, then this is equivalent to infinite
packets resp. processing until interrupted. Otherwise, a
number given as an unsigned integer will limit processing.
-r, --rand
Randomize the packet selection of the configuration file.
By default, if more than one packet is defined in a packet
configuration, packets are scheduled for transmission in a
round robin fashion. With this option, they are selected
randomly instread.
-P <uint>[-<uint>], --cpus <uint>[-<uint>]
Specify the number of processes trafgen shall fork(2) off
or list exact CPUs to use. By default trafgen will start
as many processes as CPUs that are online and pin them to
each, respectively. A single integer within interval
[1,CPUs] overrides number of processes, which will be
spawned starting from the first CPU. A pair of integers
within interval [0,CPUs-1], and separated using ''-''
represents an interval of CPUs, which will be used to
spawn worker processes.
-t <time>, --gap <time>
Specify a static inter-packet timegap in seconds,
milliseconds, microseconds, or nanoseconds:
''<num>s/ms/us/ns''. If no postfix is given default to
microseconds. If this option is given, then instead of
packet(7)'s TX_RING interface, trafgen will use sendto(2)
I/O for network packets, even if the <time> argument is 0.
This option is useful for a couple of reasons:
1) comparison between sendto(2) and TX_RING performance,
2) low-traffic packet probing for a given interval,
3) ping-like debugging with specific payload patterns.
Furthermore, the TX_RING interface does not cope with
interpacket gaps.
-b <rate>, --rate <rate>
Specify the packet send rate
<num>pps/kpps/Mpps/B/kB/MB/GB/kbit/Mbit/Gbit/KiB/MiB/GiB
units. Like with the -t/--gap option, the packets are
sent in slow mode.
-S <size>, --ring-size <size>
Manually define the TX_RING resp. TX_RING size in
''<num>KiB/MiB/GiB''. By default the size is being
determined based on the network connectivity rate.
-E <uint>, --seed <uint>
Manually set the seed for pseudo random number generator
(PRNG) in trafgen. By default, a random seed from
/dev/urandom is used to feed glibc's PRNG. If that fails,
it falls back to the unix timestamp. It can be useful to
set the seed manually in order to be able to reproduce a
trafgen session, e.g. after fuzz testing.
-u <uid>, --user <uid> resp. -g <gid>, --group <gid>
After ring setup, drop privileges to a non-root user/group
combination.
-H, --prio-high
Set this process as a high priority process in order to
achieve a higher scheduling rate resp. CPU time. This is
however not the default setting, since it could lead to
starvation of other processes, for example low priority
kernel threads.
-A, --no-sock-mem
Do not change systems default socket memory setting during
testrun. Default is to boost socket buffer memory during
the test to:
/proc/sys/net/core/rmem_default:4194304
/proc/sys/net/core/wmem_default:4194304
/proc/sys/net/core/rmem_max:104857600
/proc/sys/net/core/wmem_max:104857600
-Q, --notouch-irq
Do not reassign the NIC's IRQ CPU affinity settings.
-q, --qdisc-path
Since Linux 3.14, the kernel supports a socket option
PACKET_QDISC_BYPASS, which trafgen enables by default.
This options disables the qdisc bypass, and uses the
normal send path through the kernel's qdisc (traffic
control) layer, which can be usefully for testing the
qdisc path.
-V, --verbose
Let trafgen be more talkative and let it print the parsed
configuration and some ring buffer statistics.
-e, --example
Show a built-in packet configuration example. This might
be a good starting point for an initial packet
configuration scenario.
-C, --no-cpu-stats
Do not print CPU time statistics on exit.
-v, --version
Show version information and exit.
-h, --help
Show user help and exit.
trafgen's packet configuration syntax is fairly simple. The very
basic things one needs to know is that a configuration file is a
simple plain text file where packets are defined. It can contain
one or more packets. Packets are enclosed by opening '{' and
closing '}' braces, for example:
{ /* packet 1 content goes here ... */ }
{ /* packet 2 content goes here ... */ }
Alternatively, packets can also be specified directly on the
command line, using the same syntax as used in the configuration
files.
When trafgen is started using multiple CPUs (default), then each
of those packets will be scheduled for transmission on all CPUs
by default. However, it is possible to tell trafgen to schedule a
packet only on a particular CPU:
cpu(1): { /* packet 1 content goes here ... */ }
cpu(2-3): { /* packet 2 content goes here ... */ }
Thus, in case we have a 4 core machine with CPU0-CPU3, packet 1
will be scheduled only on CPU1, packet 2 on CPU2 and CPU3. When
using trafgen with --num option, then these constraints will
still be valid and the packet is fairly distributed among those
CPUs.
Packet content is delimited either by a comma or whitespace, or
both:
{ 0xca, 0xfe, 0xba 0xbe }
Packet content can be of the following:
hex bytes: 0xca, xff
decimal: 42
binary: 0b11110000, b11110000
octal: 011
character: 'a'
string: "hello world"
shellcode: "\x31\xdb\x8d\x43\x17\x99\xcd\x80\x31\xc9"
Thus, a quite useless packet configuration might look like this
(one can verify this when running this with trafgen in
combination with -V):
{ 0xca, 42, 0b11110000, 011, 'a', "hello world",
"\x31\xdb\x8d\x43\x17\x99\xcd\x80\x31\xc9" }
There are a couple of helper functions in trafgen's language to
make life easier to write configurations:
i) Fill with garbage functions:
byte fill function: fill(<content>, <times>): fill(0xca,
128)
compile-time random: rnd(<times>): rnd(128), rnd()
runtime random numbers: drnd(<times>): drnd(128), drnd()
compile-time counter: seqinc(<start-val>, <times>,
<increment>)
seqdec(<start-val>, <times>,
<decrement>)
runtime counter (1byte): dinc(<min-val>, <max-val>,
<increment>)
ddec(<min-val>, <max-val>,
<decrement>)
ii) Checksum helper functions (packet offsets start with 0):
IP/ICMP checksum: csumip/csumicmp(<off-from>, <off-to>)
UDP checksum: csumudp(<off-iphdr>, <off-udpdr>)
TCP checksum: csumtcp(<off-iphdr>, <off-tcphdr>)
UDP checksum (IPv6): csumudp6(<off-ip6hdr>, <off-udpdr>)
TCP checksum (IPv6): csumtcp6(<off-ip6hdr>, <off-tcphdr>)
iii) Multibyte functions, compile-time expression evaluation:
const8(<content>), c8(<content>), const16(<content>),
c16(<content>),
const32(<content>), c32(<content>), const64(<content>),
c64(<content>)
These functions write their result in network byte order into
the packet configuration, e.g. const16(0xaa) will result in ''00
aa''. Within c*() functions, it is possible to do some
arithmetics: -,+,*,/,%,&,|,<<,>>,^ E.g.
const16((((1<<8)+0x32)|0b110)*2) will be evaluated to ''02 6c''.
iv) Protocol header functions:
The protocol header functions allow to fill protocol header
fields by using following generic syntax:
<proto>(<field>=<value>,<field2>=<value2>,...,<field3>,...)
If a field is not specified, then a default value will be
used (usually 0). Protocol fields might be set in any order.
However, the offset of the fields in the resulting packet is
according to the respective protocol.
Each field might be set with a function which generates field
value at runtime by increment or randomize it. For L3/L4
protocols the checksum is calculated automatically if the
field was changed dynamically by specified function. The
following field functions are supported:
dinc - increment field value at runtime. By default
increment step is '1'. min and max parameters are used
to increment field only in the specified range, by
default original field value is used. If the field length
is greater than 4 then last 4 bytes are incremented only
(useful for MAC and IPv6 addresses):
<field> = dinc() | dinc(min, max) | dinc(min, max,
step)
drnd - randomize field value at runtime. min and max
parameters are used to randomize field only in the
specified range:
<field> = drnd() | drnd(min, max)
Example of using dynamic functions:
{
eth(saddr=aa:bb:cc:dd:ee:ff, saddr=dinc()),
ipv4(saddr=dinc()),
udp(sport=dinc(1, 13, 2), dport=drnd(80, 100))
}
Fields might be further manipulated with a function at a
specific offset:
<field>[<index>] | <field>[<index>:<length>]
<index> - relative field offset with range
0..<field.len> - 1
<length> - length/size of the value which will be
set; either 1, 2 or 4 bytes (default: 1)
The <index> starts from the field's first byte in network
order.
The syntax is similar to the one used in pcap filters
(man pcap-filter) for matching header field at a
specified offset.
Examples of using field offset (showing the effect in a
shortenet output from netsniff-ng):
1) trafgen -o lo --cpus 1 -n 3 '{
eth(da=11:22:33:44:55:66, da[0]=dinc()), tcp() }'
[ Eth MAC (00:00:00:00:00:00 =>
11:22:33:44:55:66)
[ Eth MAC (00:00:00:00:00:00 =>
12:22:33:44:55:66)
[ Eth MAC (00:00:00:00:00:00 =>
13:22:33:44:55:66)
2) trafgen -o lo --cpus 1 -n 3 '{ ipv4(da=1.2.3.4,
da[0]=dinc()), tcp() }'
[ IPv4 Addr (127.0.0.1 => 1.2.3.4)
[ IPv4 Addr (127.0.0.1 => 2.2.3.4)
[ IPv4 Addr (127.0.0.1 => 3.2.3.4)
All required lower layer headers will be filled automatically
if they were not specified by the user. The headers will be
filled in the order they were specified. Each header will be
filled with some mimimum required set of fields.
Supported protocol headers:
Ethernet : eth(da=<mac>, sa=<mac>, type=<number>)
da|daddr - Destination MAC address (default:
00:00:00:00:00:00)
sa|saddr - Source MAC address (default: device MAC
address)
etype|type|prot|proto - Ethernet type (default: 0)
PAUSE (IEEE 802.3X) : pause(code=<number>, time=<number>)
code - MAC Control opcode (default: 0x0001)
time - Pause time (default: 0)
By default Ethernet header is added with a fields:
Ethernet type - 0x8808
Destination MAC address - 01:80:C2:00:00:01
PFC : pfc(pri|prio(<number>)=<number>,
time(<number>)=<number>)
code - MAC Control opcode (default: 0x0101)
pri|prio - Priority enable vector (default: 0)
pri|prio(<number>) - Enable/disable (0 - disable, 1 -
enable) pause for priority <number> (default: 0)
time(<number>) - Set pause time for priority <number>
(default: 0)
By default Ethernet header is added with a fields:
Ethernet type - 0x8808
Destination MAC address - 01:80:C2:00:00:01
VLAN : vlan(tpid=<number>, id=<number>, dei=<number>,
tci=<number>, pcp=<number>, 1q, 1ad)
tpid|prot|proto - Tag Protocol Identifier (TPID)
(default: 0x8100)
tci - Tag Control Information (TCI) field (VLAN Id + PCP
+ DEI) (default: 0)
dei|cfi - Drop Eligible Indicator (DEI), formerly
Canonical Format Indicator (CFI) (default: 0)
pcp - Priority code point (PCP) (default: 0)
id - VLAN Identifier (default: 0)
1q - Set 802.1q header (TPID: 0x8100)
1ad - Set 802.1ad header (TPID: 0x88a8)
By default, if the lower level header is Ethernet, its
EtherType is set to 0x8100 (802.1q).
MPLS : mpls(label=<number>, tc|exp=<number>, last=<number>,
ttl=<number>)
label|lbl - MPLS label value (default: 0)
tclass|tc|exp - Traffic Class for QoS field (default: 0)
last - Bottom of stack S-flag (default: 1 for most last
label)
ttl - Time To Live (TTL) (default: 0)
By default, if the lower level header is Ethernet, its
EtherType is set to 0x8847 (MPLS Unicast). S-flag is set
automatically to 1 for the last label and resets to 0 if the
lower MPLS label was added after.
ARP : arp(htype=<number>, ptype=<number>,
op=<request|reply|number>, request, reply, smac=<mac>,
sip=<ip4_addr>, tmac=<mac>, tip=<ip4_addr>)
htype - ARP hardware type (default: 1 [Ethernet])
ptype - ARP protocol type (default: 0x0800 [IPv4])
op - ARP operation type (request/reply) (default:
request)
req|request - ARP Request operation type
reply - ARP Reply operation type
smac|sha - Sender hardware (MAC) address (default: device
MAC address)
sip|spa - Sender protocol (IPv4) address (default: device
IPv4 address)
tmac|tha - Target hardware (MAC) address (default:
00:00:00:00:00:00)
tip|tpa - Target protocol (IPv4) address (default: device
IPv4 address)
By default, the ARP operation field is set to request and the
Ethernet destination MAC address is set to the broadcast
address (ff:ff:ff:ff:ff:ff).
IPv4 : ip4|ipv4(ihl=<number>, ver=<number>, len=<number>,
csum=<number>, ttl=<number>, tos=<number>, dscp=<number>,
ecn=<number>,
id=<number>, flags=<number>, frag=<number>,
df, mf, da=<ip4_addr>, sa=<ip4_addr>,
prot[o]=<number>)
ver|version - Version field (default: 4)
ihl - Header length in number of 32-bit words (default:
5)
tos - Type of Service (ToS) field (default: 0)
dscp - Differentiated Services Code Point (DSCP,
DiffServ) field (default: 0)
ecn - Explicit Congestion Notification (ECN) field
(default: 0)
len|length - Total length of header and payload
(calculated by default)
id - IPv4 datagram identification (default: 0)
flags - IPv4 flags value (DF, MF) (default: 0)
df - Don't fragment (DF) flag (default: 0)
mf - More fragments (MF) flag (default: 0)
frag - Fragment offset field in number of 8 byte blocks
(default: 0)
ttl - Time to live (TTL) field (default: 0)
csum - Header checksum (calculated by default)
sa|saddr - Source IPv4 address (default: device IPv4
address)
da|daddr - Destination IPv4 address (default: 0.0.0.0)
prot|proto - IPv4 protocol number (default: 0)
By default, if the lower level header is Ethernet, its
EtherType field is set to 0x0800 (IPv4). If the lower level
header is IPv4, its protocol field is set to 0x4 (IP-in-IP).
IPv6 : ip6|ipv6(ver=<number>, class=<number>, flow=<number>
len=<number>, nexthdr=<number>, hoplimit=<number>,
da=<ip6_addr>, sa=<ip6_addr>)
ver|version - Version field (default: 6)
tc|tclass - Traffic class (default: 0)
fl|flow - Flow label (default: 0)
len|length - Payload length (calculated by default)
nh|nexthdr - Type of next header, i.e. transport layer
protocol number (default: 0)
hl|hoplimit|ttl - Hop limit, i.e. time to live (default:
0)
sa|saddr - Source IPv6 address (default: device IPv6
address)
da|daddr - Destination IPv6 address (default:
0:0:0:0:0:0:0:0)
By default, if the lower level header is Ethernet, its
EtherType field is set to 0x86DD (IPv6).
ICMPv4 : icmp4|icmpv4(type=<number>, code=<number>,
echorequest, echoreply, csum=<number>, mtu=<number>,
seq=<number>, id=<number>, addr=<ip4_addr>)
type - Message type (default: 0 - Echo reply)
code - Message code (default: 0)
echorequest - ICMPv4 echo (ping) request (type: 8, code:
0)
echoreply - ICMPv4 echo (ping) reply (type: 0, code: 0)
csum - Checksum of ICMPv4 header and payload (calculated
by default)
mtu - Next-hop MTU field used in 'Datagram is too big'
message type (default; 0)
seq - Sequence number used in Echo/Timestamp/Address mask
messages (default: 0)
id - Identifier used in Echo/Timestamp/Address mask
messages (default: 0)
addr - IPv4 address used in Redirect messages (default:
0.0.0.0)
Example ICMP echo request (ping):
{ icmpv4(echorequest, seq=1, id=1326) }
ICMPv6 : icmp6|icmpv6(type=<number>, echorequest, echoreply,
code=<number>, csum=<number>)
type - Message type (default: 0)
code - Code (default: 0)
echorequest - ICMPv6 echo (ping) request
echoreply - ICMPv6 echo (ping) reply
csum - Message checksum (calculated by default)
By default, if the lower level header is IPv6, its Next
Header field is set to 58 (ICMPv6).
UDP : udp(sp=<number>, dp=<number>, len=<number>,
csum=<number>)
sp|sport - Source port (default: 0)
dp|dport - Destination port (default: 0)
len|length - Length of UDP header and data (calculated by
default)
csum - Checksum field over IPv4 pseudo header (calculated
by default)
By default, if the lower level header is IPv4, its protocol
field is set to 0x11 (UDP).
TCP : tcp(sp=<number>, dp=<number>, seq=<number>,
aseq|ackseq=<number>, doff|hlen=<number>, cwr, ece|ecn, urg,
ack, psh, rst, syn, fin, win|window=<number>, csum=<number>,
urgptr=<number>)
sp|sport - Source port (default: 0)
dp|dport - Destination port (default: 0)
seq - Sequence number (default: 0)
aseq|ackseq - Acknowledgement number (default: 0)
doff|hlen - Header size (data offset) in number of 32-bit
words (default: 5)
cwr - Congestion Window Reduced (CWR) flag (default: 0)
ece|ecn - ECN-Echo (ECE) flag (default: 0)
urg - Urgent flag (default: 0)
ack - Acknowledgement flag (default: 0)
psh - Push flag (default: 0)
rst - Reset flag (default: 0)
syn - Synchronize flag (default: 0)
fin - Finish flag (default: 0)
win|window - Receive window size (default: 0)
csum - Checksum field over IPv4 pseudo header (calculated
by default)
urgptr - Urgent pointer (default: 0)
By default, if the lower level header is IPv4, its protocol
field is set to 0x6 (TCP).
Simple example of a UDP Echo packet:
{
eth(da=11:22:33:44:55:66),
ipv4(daddr=1.2.3.4)
udp(dp=7),
"Hello world"
}
Furthermore, there are two types of comments in trafgen
configuration files:
1. Multi-line C-style comments: /* put comment here */
2. Single-line Shell-style comments: # put comment here
Next to all of this, a configuration can be passed through the C
preprocessor before the trafgen compiler gets to see it with
option --cpp. To give you a taste of a more advanced example, run
''trafgen -e'', fields are commented:
/* Note: dynamic elements make trafgen slower! */
#include <stddef.h>
{
/* MAC Destination */
fill(0xff, ETH_ALEN),
/* MAC Source */
0x00, 0x02, 0xb3, drnd(3),
/* IPv4 Protocol */
c16(ETH_P_IP),
/* IPv4 Version, IHL, TOS */
0b01000101, 0,
/* IPv4 Total Len */
c16(59),
/* IPv4 Ident */
drnd(2),
/* IPv4 Flags, Frag Off */
0b01000000, 0,
/* IPv4 TTL */
64,
/* Proto TCP */
0x06,
/* IPv4 Checksum (IP header from, to) */
csumip(14, 33),
/* Source IP */
drnd(4),
/* Dest IP */
drnd(4),
/* TCP Source Port */
drnd(2),
/* TCP Dest Port */
c16(80),
/* TCP Sequence Number */
drnd(4),
/* TCP Ackn. Number */
c32(0),
/* TCP Header length + TCP SYN/ECN Flag */
c16((8 << 12) | TCP_FLAG_SYN | TCP_FLAG_ECE)
/* Window Size */
c16(16),
/* TCP Checksum (offset IP, offset TCP) */
csumtcp(14, 34),
/* TCP Options */
0x00, 0x00, 0x01, 0x01, 0x08, 0x0a, 0x06,
0x91, 0x68, 0x7d, 0x06, 0x91, 0x68, 0x6f,
/* Data blob */
"gotcha!",
}
Another real-world example by Jesper Dangaard Brouer [1]:
{
# --- ethernet header ---
0x00, 0x1b, 0x21, 0x3c, 0x9d, 0xf8, # mac destination
0x90, 0xe2, 0xba, 0x0a, 0x56, 0xb4, # mac source
const16(0x0800), # protocol
# --- ip header ---
# ipv4 version (4-bit) + ihl (4-bit), tos
0b01000101, 0,
# ipv4 total len
const16(40),
# id (note: runtime dynamic random)
drnd(2),
# ipv4 3-bit flags + 13-bit fragment offset
# 001 = more fragments
0b00100000, 0,
64, # ttl
17, # proto udp
# dynamic ip checksum (note: offsets are zero indexed)
csumip(14, 33),
192, 168, 51, 1, # source ip
192, 168, 51, 2, # dest ip
# --- udp header ---
# as this is a fragment the below stuff does not matter too
much
const16(48054), # src port
const16(43514), # dst port
const16(20), # udp length
# udp checksum can be dyn calc via csumudp(offset ip, offset
tcp)
# which is csumudp(14, 34), but for udp its allowed to be
zero
const16(0),
# payload
'A', fill(0x41, 11),
}
[1] https://marc.info/?l=linux-netdev&m=135903630614184
The above example rewritten using the header generation
functions:
{
# --- ethernet header ---
eth(da=00:1b:21:3c:9d:f8, sa=90:e2:ba:0a:56:b4)
# --- ip header ---
ipv4(id=drnd(), mf, ttl=64, sa=192.168.51.1,
da=192.168.51.2)
# --- udp header ---
udp(sport=48054, dport=43514, csum=0)
# payload
'A', fill(0x41, 11),
}
trafgen --dev eth0 --conf trafgen.cfg
This is the most simple and, probably, the most common use
of trafgen. It will generate traffic defined in the
configuration file ''trafgen.cfg'' and transmit this via
the ''eth0'' networking device. All online CPUs are used.
trafgen --dev eth0 --conf trafgen.cfg --cpus 2-4
Instead of using all online CPUs, transmit traffic from
CPUs 2, 3, and 4.
trafgen -e | trafgen -i - -o lo --cpp -n 1
This is an example where we send one packet of the built-
in example through the loopback device. The example
configuration is passed via stdin and also through the C
preprocessor before trafgen's packet compiler will see it.
trafgen --dev eth0 --conf fuzzing.cfg --smoke-test 10.0.0.1
Read the ''fuzzing.cfg'' packet configuration file (which
contains drnd() calls) and send out the generated packets
to the ''eth0'' device. After each sent packet, ping probe
the attacked host with address 10.0.0.1 to check if it's
still alive. This also means, that we utilize 1 CPU only,
and do not use the TX_RING, but sendto(2) packet I/O due
to ''slow mode''.
trafgen --dev wlan0 --rfraw --conf beacon-test.txf -V --cpus 2
As an output device ''wlan0'' is used and put into
monitoring mode, thus we are going to transmit raw 802.11
frames through the air. Use the ''beacon-test.txf''
configuration file, set trafgen into verbose mode and use
only 2 CPUs starting from CPU 0.
trafgen --dev em1 --conf frag_dos.cfg --rand --gap 1000us
Use trafgen in sendto(2) mode instead of TX_RING mode and
sleep after each sent packet a static timegap for 1000us.
Generate packets from ''frag_dos.cfg'' and select next
packets to send randomly instead of a round-robin fashion.
The output device for packets is ''em1''.
trafgen --dev eth0 --conf icmp.cfg --rand --num 1400000 -k1000
Send only 1400000 packets using the ''icmp.cfg''
configuration file and then exit trafgen. Select packets
randomly from that file for transmission and send them out
via ''eth0''. Also, trigger the kernel every 1000us for
batching the ring frames from user space (default is
10us).
trafgen --dev eth0 --conf tcp_syn.cfg -u `id -u bob` -g `id -g
bob`
Send out packets generated from the configuration file
''tcp_syn.cfg'' via the ''eth0'' networking device. After
setting up the ring for transmission, drop credentials to
the non-root user/group bob/bob.
trafgen --dev eth0 '{ fill(0xff, 6), 0x00, 0x02, 0xb3, rnd(3),
c16(0x0800), fill(0xca, 64) }' -n 1
Send out 1 invaid IPv4 packet built from command line to
all hosts.
trafgen can saturate a Gigabit Ethernet link without problems. As
always, of course, this depends on your hardware as well. Not
everywhere where it says Gigabit Ethernet on the box, will you
reach almost physical line rate! Please also read the
netsniff-ng(8) man page, section NOTE for further details about
tuning your system e.g. with tuned(8).
If you intend to use trafgen on a 10-Gbit/s Ethernet NIC, make
sure you are using a multiqueue tc(8) discipline, and make sure
that the packets you generate with trafgen will have a good
distribution among tx_hashes so that you'll actually make use of
multiqueues.
For introducing bit errors, delays with random variation and
more, there is no built-in option in trafgen. Rather, one should
reuse existing methods for that which integrate nicely with
trafgen, such as tc(8) with its different disciplines, i.e.
netem.
For more complex packet configurations, it is recommended to use
high-level scripting for generating trafgen packet configurations
in a more automated way, i.e. also to create different traffic
distributions that are common for industrial benchmarking:
Traffic model Distribution
IMIX 64:7, 570:4, 1518:1
Tolly 64:55, 78:5, 576:17, 1518:23
Cisco 64:7, 594:4, 1518:1
RPR Trimodal 64:60, 512:20, 1518:20
RPR Quadrimodal 64:50, 512:15, 1518:15, 9218:20
The low-level nature of trafgen makes trafgen rather protocol
independent and therefore useful in many scenarios when stress
testing is needed, for instance. However, if a traffic generator
with higher level packet descriptions is desired, netsniff-ng's
mausezahn(8) can be of good use as well.
For smoke/fuzz testing with trafgen, it is recommended to have a
direct link between the host you want to analyze (''victim''
machine) and the host you run trafgen on (''attacker'' machine).
If the ICMP reply from the victim fails, we assume that probably
its kernel crashed, thus we print the last sent packet together
with the seed and quit probing. It might be very unlikely to find
such a ping-of-death on modern Linux systems. However, there
might be a good chance to find it on some proprietary (e.g.
embedded) systems or buggy driver firmwares that are in the wild.
Also, fuzz testing can be done on raw 802.11 frames, of course.
In case you find a ping-of-death, please mention that you were
using trafgen in your commit message of the fix!
For old trafgen versions only, there could occur kernel crashes:
we have fixed this bug in the mainline and stable kernels under
commit 7f5c3e3a8 (''af_packet: remove BUG statement in
tpacket_destruct_skb'') and also in trafgen.
Probably the best is if you upgrade trafgen to the latest
version.
trafgen is licensed under the GNU GPL version 2.0.
trafgen was originally written for the netsniff-ng toolkit by
Daniel Borkmann. It is currently maintained by Tobias Klauser
<[email protected]> and Daniel Borkmann
<[email protected]>.
netsniff-ng(8), mausezahn(8), ifpps(8), bpfc(8), flowtop(8),
astraceroute(8), curvetun(8)
Manpage was written by Daniel Borkmann.
This page is part of the Linux netsniff-ng toolkit project. A
description of the project, and information about reporting bugs,
can be found at http://netsniff-ng.org/.
This page is part of the netsniff-ng (a free Linux networking
toolkit) project. Information about the project can be found at
⟨http://netsniff-ng.org/⟩. If you have a bug report for this
manual page, send it to [email protected]. This page
was obtained from the project's upstream Git repository
⟨https://github.com/netsniff-ng/netsniff-ng⟩ on 2024-06-14. (At
that time, the date of the most recent commit that was found in
the repository was 2023-02-01.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
Linux 03 March 2013 TRAFGEN(8)
Pages that refer to this page: astraceroute(8), bpfc(8), curvetun(8), flowtop(8), ifpps(8), mausezahn(8), netsniff-ng(8)
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