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71 lines
3.4 KiB
Plaintext
71 lines
3.4 KiB
Plaintext
The following is a demonstration of the tcpwdist.d script.
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Here the tcpwdist.d script is run for a few seconds then Ctrl-C is hit,
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# tcpwdist.d
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Tracing... Hit Ctrl-C to end.
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^C
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PID: 15300 CMD: finger @mars\0
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value ------------- Distribution ------------- count
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-1 | 0
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0 |@@@@@@@@@@@@@@@@@@@@ 1
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1 | 0
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2 |@@@@@@@@@@@@@@@@@@@@ 1
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4 | 0
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PID: 4967 CMD: /usr/lib/ssh/sshd\0
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value ------------- Distribution ------------- count
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16 | 0
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32 |@@@@@@@@@@@@@@@@@@@@ 1
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64 |@@@@@@@@@@@@@@@@@@@@ 1
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128 | 0
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PID: 9172 CMD: /usr/lib/ssh/sshd\0
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value ------------- Distribution ------------- count
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16 | 0
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32 |@@@@@@@@ 4
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64 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 14
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128 | 0
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256 | 0
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512 |@@ 1
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1024 | 0
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PID: 15301 CMD: rcp 1Mb.gz mars:/tmp\0
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value ------------- Distribution ------------- count
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0 | 0
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1 |@ 2
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2 |@ 1
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4 | 0
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8 |@ 2
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16 |@ 2
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32 | 0
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64 | 0
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128 | 0
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256 | 0
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512 | 0
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1024 | 0
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2048 | 0
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4096 | 0
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8192 | 0
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16384 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 64
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32768 | 0
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In the above output we can see the "rcp" command dominates, sending
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large writes (16 to 31 Kb) 64 times. The "sshd" ssh daemons each sent
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several smaller writes, from 32 to 127 bytes - which corresponds to
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command line activity (eg, screen width of 80 bytes). The finger command
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sent 2 bytes once, and zero data bytes once.
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These values are the TCP write payload sizes.
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The writes from the "rcp" command seem unusual at over 16 Kb each, when
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this is an Ethernet network with an MTU of 1500 bytes. The reason is that
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at this point the data has not yet been broken down into MTU sized packets,
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so we are looking at the applications behaviour as it writes to TCP.
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