关于Scapy

Scapy的是一个强大的交互式数据包处理程序（使用python编写）。它能够伪造或者解码大量的网络协议数据包，能够发送、捕捉、匹配请求和回复包等等。它可以很容易地处理一些典型操作，比如端口扫描，tracerouting，探测，单元测试，攻击或网络发现（可替代hping，NMAP，arpspoof，ARP-SK，arping，tcpdump，tethereal，P0F等）。最重要的他还有很多更优秀的特性——发送无效数据帧、注入修改的802.11数据帧、在WEP上解码加密通道（VOIP）、ARP缓存攻击（VLAN）等，这也是其他工具无法处理完成的。

安装Scapy

这里我没有使用安装包进行安装，而是直接使用命令 apt-get install python-scapy，根据提示安装相应的数据包，这里我使用的ubuntu 14.04，使用的安装包如下：

tcpreplay graphviz imagemagick python-gnuplot python-pyx ebtables python-visual sox xpdf gv hexer librsvg2-binp

>>> conf.verb=2

ython-pcapy

安装完毕后测试结果如下：

walfred@walfred-VirtualBox:~/wmw/scapy/test$ sudo scapy
Welcome to Scapy (2.2.0)
>>> IP()
<IP  |>
>>> target="www.baidu.com"
>>> ip=IP(dst=target)
>>> ip
<IP  dst=Net('www.baidu.com') |>
>>> [p for p in ip]
[<IP  dst=180.97.33.107 |>]
>>>

Scapy的使用特性

1、conf 变量保存了配置信息

>>> conf
ASN1_default_codec = <ASN1Codec BER[1]>
AS_resolver = <scapy.as_resolvers.AS_resolver_multi instance at 0xb5fd4c0c>
BTsocket   = <BluetoothL2CAPSocket: read/write packets on a connected L2CAP ...
L2listen   = <L2ListenSocket: read packets at layer 2 using Linux PF_PACKET ...
L2socket   = <L2Socket: read/write packets at layer 2 using Linux PF_PACKET ...
L3socket   = <L3PacketSocket: read/write packets at layer 3 using Linux PF_P...
auto_fragment = 1
checkIPID  = 0
checkIPaddr = 1
checkIPsrc = 1
check_TCPerror_seqack = 0
color_theme = <RastaTheme>
commands   = arpcachepoison : Poison target's cache with (your MAC,victim's ...
debug_dissector = 0
debug_match = 0
default_l2 = <class 'scapy.packet.Raw'>
emph       = <Emphasize []>
ethertypes = </etc/ethertypes/ ATMMPOA RAW_FR DNA_DL ATMFATE ATALK BPQ X25 P...
except_filter = ''
extensions_paths = '.'
histfile   = '/home/walfred/.scapy_history'
iface      = 'eth0'
iface6     = 'eth0'
interactive = True
interactive_shell = ''
ipv6_enabled = True
l2types    = 0x1 <- Dot3 (802.3) 0x1 <-> Ether (Ethernet) 0xc -> IP (IP) 0x1...
l3types    = 0x3 -> IP (IP) 0x800 <-> IP (IP) 0x806 <-> ARP (ARP) 0x86dd <->...
layers     = Packet : None NoPayload : None Raw : Raw Padding : Padding ASN1...
load_layers = ['l2', 'inet', 'dhcp', 'dns', 'dot11', 'gprs', 'hsrp', 'inet6'...
logLevel   = 20
manufdb    = </usr/wireshark/wireshark/manuf/ >
mib        = <MIB/ >
neighbor   = Ether -> Dot1Q Ether -> IP Dot3 -> LLC Dot3 -> SNAP Dot3 -> IP ...
netcache   = arp_cache: 0 valid items. Timeout=120s in6_neighbor: 0 valid it...
noenum     = <Resolve []>
padding    = 1
prog       = display = 'display' dot = 'dot' hexedit = 'hexer' pdfreader = '...
promisc    = 1
prompt     = '>>> '
protocols  = </etc/protocols/ pim ip ax_25 esp tcp ah mpls_in_ip rohc ipv6_o...
raw_layer  = <class 'scapy.packet.Raw'>
raw_summary = False
readfunc   = None
resolve    = <Resolve []>
route      = Network Netmask Gateway Iface Output IP 127.0.0.0 255.0.0.0 0.0...
route6     = Destination Next Hop iface src candidates 2400:dd01:3000:10::/6...
services_tcp = </etcrvices-tcp/ kpop zabbix_trapper noclog svn cmip_man b...
services_udp = </etcrvices-udp/ zabbix_trapper noclog cmip_man z3950 root...
session    = ''
sniff_promisc = 1
stats_classic_protocols = [<class 'scapy.layers.inet.TCP'>, <class 'scapy.la...
stats_dot11_protocols = [<class 'scapy.layers.inet.TCP'>, <class 'scapy.laye...
stealth    = 'not implemented'
temp_files = []
teredoPrefix = '2001::'
teredoServerPort = 3544
use_dnet   = False
use_pcap   = False
verb       = 1
version    = '2.2.0'
warning_threshold = 5
wepkey     = ''
>>>

更改这些配置信息也比较方便：比如修改verb属性

>>> conf.verb=2

2、数据操作

>>> IP()
<IP  |>
>>> test_ip=IP(dst="192.168.115.188")<span style="font-family: Arial, Helvetica, sans-serif;">          </span>

>>> test_ip.dst
'192.168.115.188'
>>> test_ip.ttl
64

>>> test_ip.ttl=32    修改ttl值
>>> test_ip
<IP  ttl=32 dst=192.168.115.188 |>
>>> del(test_ip.ttl)  删除tt值
>>> test_ip
<IP  dst=192.168.115.188 |>
>>> test_ip.ttl       恢复了默认的ttl值
64

>>> test_tcp=TCP()
>>> test_tcp.flags
2
>>> test_tcp.flags="SA"
>>> test_tcp.flags
18
>>> test_tcp
<TCP  flags=SA |>
>>> test_tcp.flags=23
>>> test_tcp
<TCP  flags=FSRA |>
>>> i=IP(flags="DF+MF")
>>> i.flags
3
>>> i.flags=6
>>> i
<IP  flags=DF+evil |>
>>>

>>> test_ip.src
'192.168.115.198'
>>> test_ip.dst
'192.168.115.188'
>>> del(test_ip.dst)                         注意删除后的变化
>>> test_ip.dst
'127.0.0.1'
>>> test_ip.src
'127.0.0.1'
>>> test_ip.dst="192.168.115.188"             重新设定目标地址
>>> test_ip.src
'192.168.115.198'
>>>  </div>

注：以下的“/”符号表示两个链路层的组合。这样</span><span style="font-size:18px;">下层可以层重载上一层的默认值或多个字段值。

>>> IP()
<IP  |>
>>>> IP()/TCP()
<IP  frag=0 proto=tcp |<TCP  |>>
>>>> IP(proto=55)/TCP()
<IP  frag=0 proto=55 |<TCP  >> >>>> Ether()/IP()/TCP()
<Ether  type=IPv4 |<IP  frag=0 proto=tcp |<TCP  |>>>
>>>> IP()/TCP()/"GET /HTTP/1.0\r\n\r\n"     数据部分可以直接使用字符串
<IP  frag=0 proto=tcp |<TCP  |<Raw  load='GET /HTTP/1.0\r\n\r\n' |>>>  
>>>> Ether()/IP()/UDP()
<Ether  type=IPv4 |<IP  frag=0 proto=udp |<UDP  |>>>
>>>> Ether()/IP()/IP()/UDP()
<Ether  type=IPv4 |<IP  frag=0 proto=ipencap |<IP  frag=0 proto=udp |<UDP  |>>>>>>> str(IP())
'E\x00\x00\x14\x00\x01\x00\x00@\x00|\xe7\x7f\x00\x00\x01\x7f\x00\x00\x01'
>>> IP(_)
<IP  version=4L ihl=5L tos=0x0 len=20 id=1 flags= frag=0L ttl=64 proto=hopopt chksum=0x7ce7 src=127.0.0.1 dst=127.0.0.1 |>
>>> a=Ether()/IP(dst="www.baidu.com")/TCP()/"GET /index.html HTTP/1.0 \n\n"
>>> hexdump(a)
0000   00 03 0F 19 6A 49 08 00  27 FE D8 12 08 00 45 00   ....jI..'.....E.
0010   00 43 00 01 00 00 40 06  70 78 C0 A8 73 C6 B4 61   .C....@.px..s..a
0020   21 6C 00 14 00 50 00 00  00 00 00 00 00 00 50 02   !l...P........P.
0030   20 00 B3 75 00 00 47 45  54 20 2F 69 6E 64 65 78    ..u..GET /index
0040   2E 68 74 6D 6C 20 48 54  54 50 2F 31 2E 30 20 0A   .html HTTP/1.0 .
0050   0A                                                 .
>>> b=str(a)
>>> b
"\x00\x03\x0f\x19jI\x08\x00'\xfe\xd8\x12\x08\x00E\x00\x00C\x00\x01\x00\x00@\x06px\xc0\xa8s\xc6\xb4a!l\x00\x14\x00P\x00\x00\x00\x00\x00\x00\x00\x00P\x02 \x00\xb3u\x00\x00GET /index.html HTTP/1.0 \n\n"
>>> c=Ether(b)
>>> c
<Ether  dst=00:03:0f:19:6a:49 src=08:00:27:fe:d8:12 type=IPv4 |<IP  version=4L ihl=5L tos=0x0 len=67 id=1 flags= frag=0L ttl=64 proto=tcp chksum=0x7078 src=192.168.115.198 dst=180.97.33.108 options=[] |<TCP  sport=ftp_data dport=http seq=0 ack=0 dataofs=5L reserved=0L flags=S window=8192 chksum=0xb375 urgptr=0 options=[] |<Raw  load='GET /index.html HTTP/1.0 \n\n' |>>>>>>> c.hide_defaults()  如果觉得过于冗长，可以使用这个函数隐藏
>>> c
<Ether  dst=00:03:0f:19:6a:49 src=08:00:27:fe:d8:12 type=IPv4 |<IP  ihl=5L len=67 frag=0 proto=tcp chksum=0x7078 src=192.168.115.198 dst=180.97.33.108 |<TCP  dataofs=5L chksum=0xb375 options=[] |<Raw  load='GET /index.html HTTP/1.0 \n\n' |>>>>>>> a=rdpcap("/mnt/share/test1.cap")  我使用的wireshark,保存成pcap的格式
>>> a
<test1.cap: TCP:13 UDP:53 ICMP:4 Other:3>
>>> a[9].pdfdump(layer_shift=1)
>>> a[9].psdump("/mnt/share/test1.eps",layer_shift=1)

如何产生多个数据包 
>>> a=IP(dst="www.baidu.com/30")
>>> a
<IP  dst=Net('www.baidu.com/30') |>
>>> [p for p in a]
[<IP  dst=180.97.33.104 |>, <IP  dst=180.97.33.105 |>, <IP  dst=180.97.33.106 |>, <IP  dst=180.97.33.107 |>]
>>> b=IP(ttl=[1,2,(5,9)])
>>> b
<IP  ttl=[1, 2, (5, 9)] |>
>>> [p for p in b]
[<IP  ttl=1 |>, <IP  ttl=2 |>, <IP  ttl=5 |>, <IP  ttl=6 |>, <IP  ttl=7 |>, <IP  ttl=8 |>, <IP  ttl=9 |>]
>>> c=TCP(dport=[80,443])
>>> [p for p in a/c]    产生多个数据包
[<IP  frag=0 proto=tcp dst=180.97.33.104 |<TCP  dport=http |>>, <IP  frag=0 proto=tcp dst=180.97.33.104 |<TCP  dport=https |>>,  <IP  frag=0 proto=tcp dst=180.97.33.105 |<TCP  dport=http |>>, <IP  frag=0 proto=tcp dst=180.97.33.105 |<TCP  dport=https |>>, <IP  frag=0 proto=tcp dst=180.97.33.106 |<TCP  dport=http |>>, <IP  frag=0 proto=tcp dst=180.97.33.106 |<TCP  dport=https |>>, <IP  frag=0 proto=tcp dst=180.97.33.107 |<TCP  dport=http |>>, <IP  frag=0 proto=tcp dst=180.97.33.107 |<TCP  dport=https |>>]
>>>

3、发送数据包

学习send/sendp/sr/sr1/srp 发送数据包函数使用

>>> send(IP(dst="192.168.115.188")/ICMP())  send函数工作在第三层
.
Sent 1 packets.
>>> sendp(Ether()/IP(dst="192.168.115.188",ttl=(1,4)),iface="eth0")
....
Sent 4 packets.
>>> sendp("hello ,i am walfred ",iface="eth0",loop=1,inter=0.2)  sendp函数工作在第二层，你可以选择网卡和协议
..................................................................................................................................................................................................................................................................................................................................^C
Sent 322 packets.

fuzz函数的作用：可以更改一些默认的不可以被计算的值（比如校验和checksums）,更改的值是随机的，但是类型是符合字段的值的。比如下面的例子，结果如下图对比：

>>> send(IP(dst="www.baidu.com")/UDP()/NTP(version=4),loop=2)  未使用fuzz()

>>> send(IP(dst="www.baidu.com")/fuzz(UDP()/NTP(version=4)),loop=2) 使用fuzz()

SR()函数用来来发送数据包和接收响应。该函数返回有回应的数据包和没有回应的数据包；该函数也算得上是scapy的核心了，他会返回两个列表数据，一个是answer list 另一个是unanswered list

>>> sr(IP(dst="192.168.115.1")/TCP(dport=[21,22,23]))
Begin emission:
Finished to send 3 packets.
***
Received 3 packets, got 3 answers, remaining 0 packets
Results: TCP:3 UDP:0 ICMP:0 Other:0>, Unanswered: TCP:0 UDP:0 ICMP:0 Other:0

>>> ans,unans=_    这也是scapy的核心了
>>> ans.show()
0000 IP / TCP 192.168.115.198:ftp_data > 192.168.115.1:ftp S ==> IP / TCP 192.168.115.1:ftp > 192.168.115.198:ftp_data RA / Padding
0001 IP / TCP 192.168.115.198:ftp_data > 192.168.115.1:ssh S ==> IP / TCP 192.168.115.1:ssh > 192.168.115.198:ftp_data RA / Padding
0002 IP / TCP 192.168.115.198:ftp_data > 192.168.115.1:telnet S ==> IP / TCP 192.168.115.1:telnet > 192.168.115.198:ftp_data SA / Padding 
>>>sr(IP(dst="192.168.115.1")/TCP(dport=[21,22,23]),inter=0.5,retry=-2,timeout=1)  网络环境不好时，也可以追加inter retry timeout等附加信息，

函数sr1()是sr()一个变种，只返回应答发送的分组（或分组集）。这两个函数发送的数据包必须是第3层数据包（IP，ARP等）。而函数SRP()位于第2层（以太网，802.3，等）。

>>> p=sr1(IP(dst="192.168.115.188")/ICMP()/"test")
Begin emission:
.....Finished to send 1 packets.
.*
Received 7 packets, got 1 answers, remaining 0 packets
>>> p
<IP  version=4L ihl=5L tos=0x0 len=32 id=26000 flags= frag=0L ttl=128 proto=icmp chksum=0x6c79 src=192.168.115.188 dst=192.168.115.198 options=[] |<ICMP  type=echo-reply code=0 chksum=0x1826 id=0x0 seq=0x0 |<Raw  load='test' |<Padding  load='\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' |>>>>
>>> p.show()
###[ IP ]###version= 4Lihl= 5Ltos= 0x0len= 32id= 26000flags= frag= 0Lttl= 128proto= icmpchksum= 0x6c79src= 192.168.115.188dst= 192.168.115.198\options\
###[ ICMP ]###type= echo-replycode= 0chksum= 0x1826id= 0x0seq= 0x0
###[ Raw ]###load= 'test'
###[ Padding ]###load= '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'