1dropwatch(1)                General Commands Manual               dropwatch(1)
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NAME

6       dropwatch - kernel dropped packet monitoring utility
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SYNOPSIS

9       dropwatch [-l method | list]
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DESCRIPTION

12       dropwatch  is an interactive utility for monitoring and recording pack‐
13       ets that are dropped by the kernel.
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OPTIONS

16       -l method | list, --lmethod method | list
17              Select the translation method to use when a drop alert  arrives.
18              By  default  the  raw  instruction pointer of a drop location is
19              output, but by the use of the -l option, we can assign a  trans‐
20              lation  method so that the instruction pointer can be translated
21              into function names.  Currently supported lookup methods are:
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23              list   Show all supported methods.
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25              kas    Use /proc/kallsyms  to  lookup  instruction  pointers  to
26                     function mappings.
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INTERACTIVE COMMANDS

29       start  Tells the kernel to start reporting dropped packets.
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31       stop   Tells the kernel to discontinue reporting dropped packets.
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33       exit   Exits the dropmonitor program.
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35       help   Displays summary of all commands.
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37       set alertlimit value
38              Sets a triggerpoint to stop monitoring for dropped packets after
39              value alerts have been received.
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41       set alertmode { summary | packet }
42              summary - Default mode. A summary of recent packet drops is sent
43              to  user  space. The alert includes drop locations and number of
44              drops in each location.
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46              packet - Each dropped packet is sent to user  space.  The  alert
47              includes  the  packet  itself  and various metadata such as drop
48              location and timestamp.
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50       set trunc len
51              Sets the truncation length. Reported packets will  be  truncated
52              to length len. This setting is only applicable when alertmode is
53              set to packet. By default packets are not truncated. A value  of
54              0 disables truncation.
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56       set queue len
57              Sets  the  queue  length in the kernel. When alertmode is set to
58              packet, the kernel queues dropped packets in a per-CPU drop list
59              before  preparing  a netlink message for each. This setting con‐
60              trols the queue's length.  By default this  is  limited  by  the
61              kernel to 1,000 packets. Increasing this value will increase the
62              memory utilization of the system.
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64       set sw { true | false }
65              Enables or disables the monitoring of software originated drops.
66              By default software originated drops are monitored.
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68       set hw { true | false }
69              Enables or disables the monitoring of hardware originated drops.
70              By default hardware originated drops are not monitored.
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72       show   Query existing configuration from the kernel and show it.
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74       stats  Query statistics from the kernel and show it.
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76              Tail dropped - Number of packets that could not be  enqueued  to
77              the per-CPU drop list(s).
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81Neil Horman                        Mar 2009                       dropwatch(1)