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

• 1 Setup
  • 1.1 Confguring
• 2 Examples
  • 2.1 Interrupt affinity
• 3 Commands
• 4 References
• 5 Thanks

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
 Running: 
 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: 10.10.11.2  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 
      Flags: 
 Current:
      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

Examples:

 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 10.0.0.1"    sets IP destination addres
                        (BEWARE! This generator is very aggressive!)

 pgset "dst_min 10.0.0.1"            Same as dst
 pgset "dst_max 10.0.0.254"          Set the maximum destination IP.
 pgset "src_min 10.0.0.1"            Set the minimum (or only) source IP.
 pgset "src_max 10.0.0.254"          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.

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
  • IPSRC_RND
  • TXSIZE_RND
  • IPDST_RND
  • UDPSRC_RND
  • UDPDST_RND
  • MACSRC_RND
  • MACDST_RND
• dst_min
• dst_max
• src_min
• src_max
• dst_mac
• src_mac
• clear_counters
• dst6
• src6
• flows
• flowlen

• pktgen testing
• pktgen examples
• Paper from Linux-Kongress in Erlangen 2004.
• Paper at linuxsymposium 2005 (page 11-24).

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