Wireshark - 0.99.5 Uživatelská příručka stáhnout pdf (Strana 82)

4.6. Capture files and file modes

While capturing, the underlying libpcap capturing engine will grab the packets from the network

card and keep the packet data in a (relatively) small kernel buffer. This data is read by Wireshark

and saved into the capture file(s) the user specified.

Different modes of operation are available when saving this packet data to the capture file(s).

Tip!

Working with large files (several 100 MB's) can be quite slow. If you plan to do a long

term capture or capturing from a high traffic network, think about using one of the

"Multiple files" options. This will spread the captured packets over several smaller

files which can be much more pleasant to work with.

Note!

Using Multiple files may cut context related information. Wireshark keeps context in-

formation of the loaded packet data, so it can report context related problems (like a

stream error) and keeps information about context related protocols (e.g. where data is

exchanged at the establishing phase and only referred to in later packets). As it keeps

this information only for the loaded file, using one of the multiple file modes may cut

these contexts. If the establishing phase is saved in one file and the things you would

like to see is in another, you might not see some of the valuable context related inform-

ation.

Tip!

Information about the folders used for the capture file(s), can be found in Appendix A,

Files and Folders.

Table 4.1. Capture file mode selected by capture options

"File" option "Use multiple

files" option

"Ring buffer

with n files" op-

tion

Mode Resulting file-

name(s) used

- - - Single temporary

file

etherXXXXXX

(where XXXXXX is

a unique number)

foo.cap - - Single named file foo.cap

foo.cap x - Multiple files,

continuous

foo_00001_2004020

5110102.cap,

foo_00002_2004020

5110102.cap, ...

foo.cap x x Multiple files,

ring buffer

foo_00001_2004020

5110102.cap,

foo_00002_2004020

5110102.cap, ...

Single temporary file A temporary file will be created and used (this is the default).

After the capturing is stopped, this file can be saved later un-

der a user specified name.

Capturing Live Network Data

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