pktgen

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介绍 Linux 内核发包工具 pktgen 及其配置、使用方法和样例。

什么是 pktgen

pktgen 是一款 Linux 发包工具，可在内核高速发包。

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

使能 pktgen

内核配置文件开启 CONFIG_NET_PKTGEN，通过查看是否有 /proc/net/pktgen/ 目录确认是否编译 OK。

使用 pktgen 发包

  • 添加设备
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echo "add_device eth3" > /proc/net/pktgen/kpktgend_0
  • 配置报文
    配置方法，样例仅给出部分配置
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    echo "pkt_size 64" > /proc/net/pktgen/eth3
    echo "count 1000000" > /proc/net/pktgen/eth3
    echo "dst_mac aa:bb:cc:dd:ee:ff" > /proc/net/pktgen/eth3

查看配置结果：

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cat /proc/net/pktgen/eth3

  • 发送报文
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echo "start" > /proc/net/pktgen/pgctrl

查看发送结果：

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cat /proc/net/pktgen/eth3

发包样例

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[1209-20:29:14:517] root@ubuntu:/proc/net/pktgen# echo "pkt_size 1500" > /proc/net/pktgen/eth3   
[1209-20:29:26:980] root@ubuntu:/proc/net/pktgen# echo "count 1000000" > /proc/net/pktgen/eth3         
[1209-20:29:29:862] root@ubuntu:/proc/net/pktgen# echo "start" > /proc/net/pktgen/pgctrl      
[1209-20:29:48:407] root@ubuntu:/proc/net/pktgen# cat /proc/net/pktgen/eth3                   
[1209-20:29:48:430] Params: count 1000000  min_pkt_size: 1500  max_pkt_size: 1500
[1209-20:29:48:435]      frags: 0  delay: 0  clone_skb: 0  ifname: eth3
[1209-20:29:48:437]      flows: 0 flowlen: 0
[1209-20:29:48:441]      queue_map_min: 0  queue_map_max: 0
[1209-20:29:48:444]      dst_min:   dst_max: 
[1209-20:29:48:447]         src_min:   src_max: 
[1209-20:29:48:452]      src_mac: 02:10:18:2c:f8:0e dst_mac: 00:00:00:00:00:00
[1209-20:29:48:458]      udp_src_min: 9  udp_src_max: 9  udp_dst_min: 9  udp_dst_max: 9
[1209-20:29:48:460]      src_mac_count: 0  dst_mac_count: 0
[1209-20:29:48:464]      Flags: 
[1209-20:29:48:464] Current:
[1209-20:29:48:467]      pkts-sofar: 1000000  errors: 0
[1209-20:29:48:472]      started: 3219370012us  stopped: 3233111900us idle: 299798us
[1209-20:29:48:477]      seq_num: 1000001  cur_dst_mac_offset: 0  cur_src_mac_offset: 0
[1209-20:29:48:481]      cur_saddr: 192.168.2.1  cur_daddr: 0.0.0.0
[1209-20:29:48:486]      cur_udp_dst: 9  cur_udp_src: 9
[1209-20:29:48:490]      cur_queue_map: 0
[1209-20:29:48:491]      flows: 0
[1209-20:29:48:496] Result: OK: 13741888(c13442090+d299798) usec, 1000000 (1500byte,0frags)
[1209-20:29:48:499]   72770pps 873Mb/sec (873240000bps) errors: 0
[1209-20:30:05:839] root@ubuntu:/proc/net/pktgen#

完整说明

From linuxfoundation.org pktgen：

Setup

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:

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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
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    # 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:

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# 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

Confguring

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

Examples:

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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.

Examples

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.

Commands

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