2009-03-21 20:43:56 +00:00
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2015-01-06 18:58:31 +00:00
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.TH PCAP_DATALINK 3PCAP "13 October 2013"
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2009-03-21 20:43:56 +00:00
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.SH NAME
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pcap_datalink \- get the link-layer header type
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.SH SYNOPSIS
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.nf
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.ft B
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#include <pcap/pcap.h>
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.ft
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.LP
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.ft B
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int pcap_datalink(pcap_t *p);
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.ft
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.fi
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.SH DESCRIPTION
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.B pcap_datalink()
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2012-01-31 17:22:07 +00:00
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returns the link-layer header type for the live capture or ``savefile''
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2009-03-21 20:43:56 +00:00
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specified by
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.IR p .
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2015-01-06 18:58:31 +00:00
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.PP
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It must not be called on a pcap descriptor created by
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.B pcap_create()
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that has not yet been activated by
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.BR pcap_activate() .
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.PP
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.I http://www.tcpdump.org/linktypes.html
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lists the values
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.B pcap_datalink()
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can return and describes the packet formats that
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correspond to those values.
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.PP
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Do
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.B NOT
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assume that the packets for a given capture or ``savefile`` will have
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any given link-layer header type, such as
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.B DLT_EN10MB
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for Ethernet. For example, the "any" device on Linux will have a
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link-layer header type of
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.B DLT_LINUX_SLL
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even if all devices on the system at the time the "any" device is opened
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have some other data link type, such as
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.B DLT_EN10MB
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for Ethernet.
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.SH RETURN VALUE
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.B pcap_datalink()
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returns the link-layer header type on success and
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.B PCAP_ERROR_NOT_ACTIVATED
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if called on a capture handle that has been created but not activated.
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2009-03-21 20:43:56 +00:00
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.SH SEE ALSO
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pcap(3PCAP), pcap-linktype(@MAN_MISC_INFO@)
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