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Linux packet generator is a tool to generate packets at very high speed in the kernel.



Enable CONFIG_NET_PKTGEN to compile and build pktgen.o either in kernel or as module. Module is preferred. insmod pktgen if needed. Once running pktgen creates a thread on each CPU where each thread has affinty it's CPU. Monitoring and controlling is done via /proc. Easiest to select a suitable a sample script and configure.

On a dual CPU:

 ps aux | grep pkt
 root       129  0.3  0.0     0    0 ?        SW    2003 523:20 [pktgen/0]
 root       130  0.3  0.0     0    0 ?        SW    2003 509:50 [pktgen/1]

For montoring and control pktgen creates:

  • /proc/net/pktgen/pgctrl
  • /proc/net/pktgen/kpktgend_X
 # cat /proc/net/pktgen/kpktgend_0 
 Name: kpktgend_0  max_before_softirq: 10000
 Stopped: eth1 
 Result: OK: max_before_softirq=10000

Most important the devices assigned to thread. Note! A device can only belong to one thread.

  • /proc/net/pktgen/ethX

Param section holds configured info. Current hold running stats. Result is printed after run or after interruption. Example:

 # cat /proc/net/pktgen/eth1
 Params: count 10000000  min_pkt_size: 60  max_pkt_size: 60
      frags: 0  delay: 0  clone_skb: 1000000  ifname: eth1
      flows: 0 flowlen: 0
      dst_min:  dst_max: 
      src_min:   src_max: 
      src_mac: 00:00:00:00:00:00  dst_mac: 00:04:23:AC:FD:82
      udp_src_min: 9  udp_src_max: 9  udp_dst_min: 9  udp_dst_max: 9
      src_mac_count: 0  dst_mac_count: 0 
      pkts-sofar: 10000000  errors: 39664
      started: 1103053986245187us  stopped: 1103053999346329us idle: 880401us
      seq_num: 10000011  cur_dst_mac_offset: 0  cur_src_mac_offset: 0
      cur_saddr: 0x10a0a0a  cur_daddr: 0x20b0a0a
      cur_udp_dst: 9  cur_udp_src: 9
      flows: 0
 Result: OK: 13101142(c12220741+d880401) usec, 10000000 (60byte,0frags)
   763292pps 390Mb/sec (390805504bps) errors: 39664


This is done via the /proc interface easiest done via pgset in the scripts


 pgset "clone_skb 1"     sets the number of copies of the same packet
 pgset "clone_skb 0"     use single SKB for all transmits
 pgset "pkt_size 9014"   sets packet size to 9014
 pgset "frags 5"         packet will consist of 5 fragments
 pgset "count 200000"    sets number of packets to send, set to zero
                        for continious sends untill explicitl stopped.
 pgset "delay 5000"      adds delay to hard_start_xmit(). nanoseconds
 pgset "dst"    sets IP destination addres
                        (BEWARE! This generator is very aggressive!)
 pgset "dst_min"            Same as dst
 pgset "dst_max"          Set the maximum destination IP.
 pgset "src_min"            Set the minimum (or only) source IP.
 pgset "src_max"          Set the maximum source IP.
 pgset "dst6 fec0::1"     IPV6 destination address
 pgset "src6 fec0::2"     IPV6 source address
 pgset "dstmac 00:00:00:00:00:00"    sets MAC destination address
 pgset "srcmac 00:00:00:00:00:00"    sets MAC source address
 pgset "src_mac_count 1" Sets the number of MACs we'll range through.  
                        The 'minimum' MAC is what you set with srcmac.
 pgset "dst_mac_count 1" Sets the number of MACs we'll range through.
                        The 'minimum' MAC is what you set with dstmac.
 pgset "flag [name]"     Set a flag to determine behaviour.  Current flags
                        are: IPSRC_RND #IP Source is random (between min/max),
                             IPDST_RND, UDPSRC_RND,
                             UDPDST_RND, MACSRC_RND, MACDST_RND
  pgset "udp_src_min 9"   set UDP source port min, If < udp_src_max, then
                        cycle through the port range.
  pgset "udp_src_max 9"   set UDP source port max.
  pgset "udp_dst_min 9"   set UDP destination port min, If < udp_dst_max, then
                        cycle through the port range.
  pgset "udp_dst_max 9"   set UDP destination port max.
  pgset stop    	          aborts injection. Also, ^C aborts generator.


A collection of small tutorial scripts for pktgen is in expamples dir.

  • pktgen.conf-1-1 # 1 CPU 1 dev
  • pktgen.conf-1-2 # 1 CPU 2 dev
  • pktgen.conf-2-1 # 2 CPU's 1 dev
  • pktgen.conf-2-2 # 2 CPU's 2 dev
  • pktgen.conf-1-1-rdos # 1 CPU 1 dev w. route DoS
  • pktgen.conf-1-1-ip6 # 1 CPU 1 dev ipv6
  • pktgen.conf-1-1-ip6-rdos # 1 CPU 1 dev ipv6 w. route DoS
  • pktgen.conf-1-1-flows # 1 CPU 1 dev multiple flows.

Run in shell: ./pktgen.conf-X-Y It does all the setup including sending.

Interrupt affinity

Note when adding devices to a specific CPU there good idea to also assign /proc/irq/XX/smp_affinity so the TX-interrupts gets bound to the same CPU. as this reduces cache bouncing when freeing skb's.


Pgcontrol commands:

  • start
  • stop

Thread commands:

  • add_device
  • rem_device_all
  • max_before_softirq

Device commands:

  • count
  • clone_skb
  • debug
  • frags
  • delay
  • src_mac_count
  • dst_mac_count
  • pkt_size
  • min_pkt_size
  • max_pkt_size
  • udp_src_min
  • udp_src_max
  • udp_dst_min
  • udp_dst_max
  • flag
  • dst_min
  • dst_max
  • src_min
  • src_max
  • dst_mac
  • src_mac
  • clear_counters
  • dst6
  • src6
  • flows
  • flowlen



Grant Grundler for testing on IA-64 and parisc, Harald Welte, Lennert Buytenhek Stephen Hemminger, Andi Kleen, Dave Miller and many others.

networking/pktgen.txt · Last modified: 2016/07/19 01:22 (external edit)