08-05-2015
TCPdump
I've recently started learning to use TCPdump, and I find it pretty interesting. There's one thing I don't understand. When I tell it to capture packets on, say, the WiFi interface en1, it often captures packets sent or received by other hosts on the network. How can it do this? My understanding is that on a switched network, a host will only receive packets destined for that host. How is it that I can see packets destined for other hosts?
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I have two net-card. one is 172.16.24.99(ENG) ,another is 172.16.25.99(ENG-B). Both masks is 255.255.255.0.
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Hi, I got the following question regarding tcpdump and I would appreciate your help/feedback:
--Scenario
I am instructed to capture the network traffic by getting the tcpdump data/files of our network for every hour.
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Some of the connections are still open when the capture is done... (1 Reply)
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i would like to know about tcpdump
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- time
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then i use command like this
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i would like to know about tcpdump
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Hi,
I want to capture TCPDUMP of traffic, I tried doing this but did not find success..can anyone plz correct it.
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bash: tcpdump: command not found
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Hi Everyone,
anyone face "tcpdump -i any" does not work? i mean if i use -i eth0, can capture eth0, or use -i eth1 also can. but then tcpdump -i any, seems cannot capture packets. :confused:
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Hi.
Need Help with TcpDump
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LEARN ABOUT DEBIAN
pcap_stats
PCAP_STATS(3PCAP) PCAP_STATS(3PCAP)
NAME
pcap_stats - get capture statistics
SYNOPSIS
#include <pcap/pcap.h>
int pcap_stats(pcap_t *p, struct pcap_stat *ps);
DESCRIPTION
pcap_stats() fills in the struct pcap_stat pointed to by its second argument. The values represent packet statistics from the start of the
run to the time of the call.
pcap_stats() is supported only on live captures, not on ``savefiles''; no statistics are stored in ``savefiles'', so no statistics are
available when reading from a ``savefile''.
A struct pcap_stat has the following members:
ps_recv
number of packets received;
ps_drop
number of packets dropped because there was no room in the operating system's buffer when they arrived, because packets
weren't being read fast enough;
ps_ifdrop
number of packets dropped by the network interface or its driver.
The statistics do not behave the same way on all platforms. ps_recv might count packets whether they passed any filter set with pcap_set-
filter(3PCAP) or not, or it might count only packets that pass the filter. It also might, or might not, count packets dropped because
there was no room in the operating system's buffer when they arrived. ps_drop is not available on all platforms; it is zero on platforms
where it's not available. If packet filtering is done in libpcap, rather than in the operating system, it would count packets that don't
pass the filter. Both ps_recv and ps_drop might, or might not, count packets not yet read from the operating system and thus not yet seen
by the application. ps_ifdrop might, or might not, be implemented; if it's zero, that might mean that no packets were dropped by the
interface, or it might mean that the statistic is unavailable, so it should not be treated as an indication that the interface did not drop
any packets.
RETURN VALUE
pcap_stats() returns 0 on success and returns -1 if there is an error or if p doesn't support packet statistics. If -1 is returned,
pcap_geterr() or pcap_perror() may be called with p as an argument to fetch or display the error text.
SEE ALSO
pcap(3PCAP), pcap_geterr(3PCAP)
7 September 2009 PCAP_STATS(3PCAP)