帮酷LOGO
0 0 评论
  • 显示原文与译文双语对照的内容
文章标签:TCP  network  Tcpdump  
the TCPdump network dissector. now moved to:

  • 源代码名称:tcpdump
  • 源代码网址:http://www.github.com/the-tcpdump-group/tcpdump
  • tcpdump源代码文档
  • tcpdump源代码下载
  • Git URL:
    git://www.github.com/the-tcpdump-group/tcpdump.git
  • Git Clone代码到本地:
    git clone http://www.github.com/the-tcpdump-group/tcpdump
  • Subversion代码到本地:
    $ svn co --depth empty http://www.github.com/the-tcpdump-group/tcpdump
    Checked out revision 1.
    $ cd repo
    $ svn up trunk
    
  • tcpdump

    要报告安全问题,请发送一个 E-mail 到 security@tcpdump.org 服务器。

    报告 Bug 及其他问题,贡献补丁,请求特性,提供通用反馈等,请参阅在tcpdump源树 root 中提供的文件。

    Tcpdump 4. x. y 现在由"Tcpdump组"维护,请参见 www.tcpdump.org

    匿名Git可以通过以下方式提供:

    
    git clone git://bpf.tcpdump.org/tcpdump
    
    
    
    

    以前来自Lawrence国家实验室网络研究组 tcpdump@ee.lbl.gov
    ftp://ftp.ee.lbl.gov/old/tcpdump.tar.Z ( 3 4 )

    这个目录包含tcpdump的源代码,一个用于网络监视和数据获取的工具。 这个软件最初是由Lawrence国家实验室的网络研究小组开发的。 原始发行版可以通过匿名ftp到 ftp.ee.lbl.gov,在 tcpdump.tar.Z 中。 最近的开发是在 tcpdump.org, http://www.tcpdump.org/ 执行的。

    Tcpdump使用用户级的,独立于用户级数据包捕获的系统独立接口。 在构建tcpdump之前,首先必须检索并构建 libpcap,也最初由LBL来维护,现在由 tcpdump.org; 来查看 http://www.tcpdump.org/。

    生成libpcap之后,你可以使用文件中的过程构建 tcpdump。

    这个程序是基于"输入的etherfind"的,虽然etherfind代码不存在。 它最初是由Van编写的,作为正在进行的研究项目,用于调查和改进tcp和互联网网关性能。 最初取自太阳etherfind的程序的部分后来由LBL的Steven McCanne编写。 to没有在tcpdump提供的规范中写这些代码,为了确保没有私有代码痕迹,Steve没有访问tcpdump或者etherfind的源代码。

    在过去几年中,由于互联网社区( 只浏览 CHANGES 文件)的优秀贡献,tcpdump已经得到了稳步的改进。 我们感谢所有的输入。

    Richard在他的"tcp/ip说明,卷 1"中对因特网协议给予了很好的处理。 如果你想了解更多关于tcpdump的知识,以及如何解释它的输出,那就。

    可以从网络流量归档中查看和分析用于查看和分析tcpdump跟踪文件的一些工具:

    tcpdump用户可能发现有用的另一种工具是 tcpslice:

    它是一个程序,可以用来提取tcpdump二进制跟踪文件的一部分。 有关详细信息和文档,请参阅上发行版。

    当前版本可以在 www.tcpdump.org 找到。

    • TCPdump组

    原文作者:Steve McCanne,Craig Leres,Van Jacobson

    
    This directory also contains some short awk programs intended as
    
    
    examples of ways to reduce tcpdump data when you're tracking
    
    
    particular network problems:
    
    
    
    send-ack.awk
    
    
     Simplifies the tcpdump trace for an ftp (or other unidirectional
    
    
     tcp transfer). Since we assume that one host only sends and
    
    
     the other only acks, all address information is left off and
    
    
     we just note if the packet is a"send" or an"ack".
    
    
    
     There is one output line per line of the original trace.
    
    
     Field 1 is the packet time in decimal seconds, relative
    
    
     to the start of the conversation. Field 2 is delta-time
    
    
     from last packet. Field 3 is packet type/direction.
    
    
    "Send" means data going from sender to receiver,"ack"
    
    
     means an ack going from the receiver to the sender. A
    
    
     preceding"*" indicates that the data is a retransmission.
    
    
     A preceding"-" indicates a hole in the sequence space
    
    
     (i.e., missing packet(s)), a"#" means an odd-size (not max
    
    
     seg size) packet. Field 4 has the packet flags
    
    
     (same format as raw trace). Field 5 is the sequence
    
    
     number (start seq. num for sender, next expected seq number
    
    
     for acks). The number in parens following an ack is
    
    
     the delta-time from the first send of the packet to the
    
    
     ack. A number in parens following a send is the
    
    
     delta-time from the first send of the packet to the
    
    
     current send (on duplicate packets only). Duplicate
    
    
     sends or acks have a number in square brackets showing
    
    
     the number of duplicates so far.
    
    
    
     Here is a short sample from near the start of an ftp:
    
    
     3.00 0.20 send. 512
    
    
     3.20 0.20 ack. 1024 (0.20)
    
    
     3.20 0.00 send P 1024
    
    
     3.40 0.20 ack. 1536 (0.20)
    
    
     3.80 0.40 * send. 0 (3.80) [2]
    
    
     3.82 0.02 * ack. 1536 (0.62) [2]
    
    
     Three seconds into the conversation, bytes 512 through 1023
    
    
     were sent. 200ms later they were acked. Shortly thereafter
    
    
     bytes 1024-1535 were sent and again acked after 200ms.
    
    
     Then, for no apparent reason, 0-511 is retransmitted, 3.8
    
    
     seconds after its initial send (the round trip time for this
    
    
     ftp was 1sec, +-500ms). Since the receiver is expecting
    
    
     1536, 1536 is re-acked when 0 arrives.
    
    
    
    packetdat.awk
    
    
     Computes chunk summary data for an ftp (or similar
    
    
     unidirectional tcp transfer). [A"chunk" refers to
    
    
     a chunk of the sequence space -- essentially the packet
    
    
     sequence number divided by the max segment size.]
    
    
    
     A summary line is printed showing the number of chunks,
    
    
     the number of packets it took to send that many chunks
    
    
     (if there are no lost or duplicated packets, the number
    
    
     of packets should equal the number of chunks) and the
    
    
     number of acks.
    
    
    
     Following the summary line is one line of information
    
    
     per chunk. The line contains eight fields:
    
    
     1 - the chunk number
    
    
     2 - the start sequence number for this chunk
    
    
     3 - time of first send
    
    
     4 - time of last send
    
    
     5 - time of first ack
    
    
     6 - time of last ack
    
    
     7 - number of times chunk was sent
    
    
     8 - number of times chunk was acked
    
    
     (all times are in decimal seconds, relative to the start
    
    
     of the conversation.)
    
    
    
     As an example, here is the first part of the output for
    
    
     an ftp trace:
    
    
    
     # 134 chunks. 536 packets sent. 508 acks.
    
    
     1 1 0.00 5.80 0.20 0.20 4 1
    
    
     2 513 0.28 6.20 0.40 0.40 4 1
    
    
     3 1025 1.16 6.32 1.20 1.20 4 1
    
    
     4 1561 1.86 15.00 2.00 2.00 6 1
    
    
     5 2049 2.16 15.44 2.20 2.20 5 1
    
    
     6 2585 2.64 16.44 2.80 2.80 5 1
    
    
     7 3073 3.00 16.66 3.20 3.20 4 1
    
    
     8 3609 3.20 17.24 3.40 5.82 4 11
    
    
     9 4097 6.02 6.58 6.20 6.80 2 5
    
    
    
     This says that 134 chunks were transferred (about 70K
    
    
     since the average packet size was 512 bytes). It took
    
    
     536 packets to transfer the data (i.e., on the average
    
    
     each chunk was transmitted four times). Looking at,
    
    
     say, chunk 4, we see it represents the 512 bytes of
    
    
     sequence space from 1561 to 2048. It was first sent
    
    
     1.86 seconds into the conversation. It was last
    
    
     sent 15 seconds into the conversation and was sent
    
    
     a total of 6 times (i.e., it was retransmitted every
    
    
     2 seconds on the average). It was acked once, 140ms
    
    
     after it first arrived.
    
    
    
    stime.awk
    
    
    atime.awk
    
    
     Output one line per send or ack, respectively, in the form
    
    
     <time> <seq. number>
    
    
     where <time> is the time in seconds since the start of the
    
    
     transfer and <seq. number> is the sequence number being sent
    
    
     or acked. I typically plot this data looking for suspicious
    
    
     patterns.
    
    
    
    The problem I was looking at was the bulk-data-transfer
    
    
    throughput of medium delay network paths (1-6 sec. round trip
    
    
    time) under typical DARPA Internet conditions. The trace of the
    
    
    ftp transfer of a large file was used as the raw data source.
    
    
    The method was:
    
    
    
     - On a local host (but not the Sun running tcpdump), connect to
    
    
     the remote ftp.
    
    
    
     - On the monitor Sun, start the trace going. E.g.,
    
    
     tcpdump host local-host and remote-host and port ftp-data> tracefile
    
    
    
     - On local, do either a get or put of a large file (~500KB),
    
    
     preferably to the null device (to minimize effects like
    
    
     closing the receive window while waiting for a disk write).
    
    
    
     - When transfer is finished, stop tcpdump. Use awk to make up
    
    
     two files of summary data (maxsize is the maximum packet size,
    
    
     tracedata is the file of tcpdump tracedata):
    
    
     awk -f send-ack.awk packetsize=avgsize tracedata> sa
    
    
     awk -f packetdat.awk packetsize=avgsize tracedata> pd
    
    
    
     - While the summary data files are printing, take a look at
    
    
     how the transfer behaved:
    
    
     awk -f stime.awk tracedata | xgraph
    
    
     (90% of what you learn seems to happen in this step).
    
    
    
     - Do all of the 上面 steps several times, both directions,
    
    
     at different times of day, with different protocol
    
    
     implementations on the other end.
    
    
    
     - Using one of the Unix data analysis packages (in my case,
    
    
     S and Gary Perlman's Unix|Stat), spend a few months staring
    
    
     at the data.
    
    
    
     - Change something in the local protocol implementation and
    
    
     redo the steps 上面.
    
    
    
     - Once a week, tell your funding agent that you're discovering
    
    
     wonderful things and you'll write up that research report
    
    
    "real soon now".
    
    
    
    


    文章标签:network  TCP  Tcpdump  

    Copyright © 2011 HelpLib All rights reserved.    知识分享协议 京ICP备05059198号-3  |  如果智培  |  酷兔英语