=== Does Wireshark work on older versions of Windows such as Windows 7?
Each major release branch of Wireshark supports the versions of Windows that are within their product lifecycle at the time of the “.0” release for that branch.
For example, Wireshark 3.2.0 was released in December 2019, shortly before Windows 7 reached the end of its extended support in January 2020. As a result, each of the Wireshark 3.2._x_ releases supports Windows 7, even after January 2020.
See the
link:https://www.wireshark.org/docs/wsug_html_chunked/ChIntroPlatforms.html[Microsoft Windows section of the User’s Guide]
and the
link:https://wiki.wireshark.org/Development/LifeCycle[End Of Life Planning section of the Release Life Cycle wiki page]
for more details.
Npcap might not work well on Windows 8 and earlier, so you might want to install WinPcap instead.
=== I have an XXX network card on my machine; if I try to capture on it, why does my machine crash or reset itself?
This is almost certainly a problem with one or more of:
* the operating system you're using;
* the device driver for the interface you're using;
* the libpcap/Npcap library and, if this is Windows, the Npcap device
driver;
so:
* if you are using Windows, see https://nmap.org/npcap/[the Npcap
support page] - check the "Patches, Bug Reports, Questions, Suggestions,
etc" section;
* if you are using some Linux distribution, some version of BSD, or some
other UNIX-flavored OS, you should report the problem to the company or
organization that produces the OS (in the case of a Linux distribution,
report the problem to whoever produces the distribution).
=== Why does my machine crash or reset itself when I select "Start" from the "Capture" menu or select "Preferences" from the "Edit" menu?
Both of those operations cause Wireshark to try to build a list of
the interfaces that it can open; it does so by getting a list of
interfaces and trying to open them. There is probably an OS, driver, or,
for Windows, Npcap bug that causes the system to crash when this
happens; see the previous question.
== Capturing packets
[[promiscsniff]]
=== When I use Wireshark to capture packets, why do I see only packets to and from my machine, or not see all the traffic I'm expecting to see from or to the machine I'm trying to monitor?
This might be because the interface on which you're capturing is
plugged into an Ethernet or Token Ring switch; on a switched network,
unicast traffic between two ports will not necessarily appear on other
ports - only broadcast and multicast traffic will be sent to all ports.
Note that even if your machine is plugged into a hub, the "hub" may be
a switched hub, in which case you're still on a switched network.
Note also that on the Linksys Web site, they say that their
auto-sensing hubs "broadcast the 10Mb packets to the port that operate
at 10Mb only and broadcast the 100Mb packets to the ports that operate
at 100Mb only", which would indicate that if you sniff on a 10Mb port,
you will not see traffic coming sent to a 100Mb port, and _vice versa_.
This problem has also been reported for Netgear dual-speed hubs, and may
exist for other "auto-sensing" or "dual-speed" hubs.
Some switches have the ability to replicate all traffic on all ports to
a single port so that you can plug your analyzer into that single port
to sniff all traffic. You would have to check the documentation for the
switch to see if this is possible and, if so, to see how to do this. See
https://wiki.wireshark.org/SwitchReference[the switch reference page] on
https://wiki.wireshark.org/[the Wireshark Wiki] for information on some
switches. (Note that it's a Wiki, so you can update or fix that
information, or add additional information on those switches or
information on new switches, yourself.)
Note also that many firewall/NAT boxes have a switch built into them;
this includes many of the "cable/DSL router" boxes. If you have a box of
that sort, that has a switch with some number of Ethernet ports into
which you plug machines on your network, and another Ethernet port used
to connect to a cable or DSL modem, you can, at least, sniff traffic
between the machines on your network and the Internet by plugging the
Ethernet port on the router going to the modem, the Ethernet port on the
modem, and the machine on which you're running Wireshark into a hub
(make sure it's not a switching hub, and that, if it's a dual-speed hub,
all three of those ports are running at the same speed.
If your machine is _not_ plugged into a switched network or a
dual-speed hub, or it is plugged into a switched network but the port is
set up to have all traffic replicated to it, the problem might be that
the network interface on which you're capturing doesn't support
"promiscuous" mode, or because your OS can't put the interface into
promiscuous mode. Normally, network interfaces supply to the host only:
* packets sent to one of that host's link-layer addresses;
* broadcast packets;
* multicast packets sent to a multicast address that the host has
configured the interface to accept.
Most network interfaces can also be put in "promiscuous" mode, in which
they supply to the host all network packets they see. Wireshark will try
to put the interface on which it's capturing into promiscuous mode
unless the "Capture packets in promiscuous mode" option is turned off in
the "Capture Options" dialog box, and TShark will try to put the
interface on which it's capturing into promiscuous mode unless the `-p`
option was specified. However, some network interfaces don't support
promiscuous mode, and some OSes might not allow interfaces to be put
into promiscuous mode.
If the interface is not running in promiscuous mode, it won't see any
traffic that isn't intended to be seen by your machine. It *will* see
broadcast packets, and multicast packets sent to a multicast MAC address
the interface is set up to receive.
You should ask the vendor of your network interface whether it supports
promiscuous mode. If it does, you should ask whoever supplied the driver
for the interface (the vendor, or the supplier of the OS you're running
on your machine) whether it supports promiscuous mode with that network
interface.
In the case of token ring interfaces, the drivers for some of them, on
Windows, may require you to enable promiscuous mode in order to capture
in promiscuous mode. See
https://wiki.wireshark.org/CaptureSetup/TokenRing[the Wireshark Wiki
item on Token Ring capturing] for details.
In the case of wireless LAN interfaces, it appears that, when those
interfaces are promiscuously sniffing, they're running in a
significantly different mode from the mode that they run in when they're
just acting as network interfaces (to the extent that it would be a
significant effort for those drivers to support for promiscuously
sniffing _and_ acting as regular network interfaces at the same time),
so it may be that Windows drivers for those interfaces don't support
promiscuous mode.
=== When I capture with Wireshark, why can't I see any TCP packets other than packets to and from my machine, even though another analyzer on the network sees those packets?
You're probably not seeing _any_ packets other than unicast packets
to or from your machine, and broadcast and multicast packets; a switch
will normally send to a port only unicast traffic sent to the MAC
address for the interface on that port, and broadcast and multicast
traffic - it won't send to that port unicast traffic sent to a MAC
address for some other interface - and a network interface not in
promiscuous mode will receive only unicast traffic sent to the MAC
address for that interface, broadcast traffic, and multicast traffic
sent to a multicast MAC address the interface is set up to receive.
TCP doesn't use broadcast or multicast, so you will only see your own
TCP traffic, but UDP services may use broadcast or multicast so you'll
see some UDP traffic - however, this is not a problem with TCP traffic,
it's a problem with unicast traffic, as you also won't see all UDP
traffic between other machines.
I.e., this is probably link:#promiscsniff[the same question as this
earlier one]; see the response to that question.
=== Why am I only seeing ARP packets when I try to capture traffic?
You're probably on a switched network, and running Wireshark on a
machine that's not sending traffic to the switch and not being sent any
traffic from other machines on the switch. ARP packets are often
broadcast packets, which are sent to all switch ports.
I.e., this is probably link:#promiscsniff[the same question as this
earlier one]; see the response to that question.
=== Why am I not seeing any traffic when I try to capture traffic?
Is the machine running Wireshark sending out any traffic on the
network interface on which you're capturing, or receiving any traffic on
that network, or is there any broadcast traffic on the network or
multicast traffic to a multicast group to which the machine running
Wireshark belongs?
If not, this may just be a problem with promiscuous sniffing, either
due to running on a switched network or a dual-speed hub, or due to
problems with the interface not supporting promiscuous mode; see the
response to link:#promiscsniff[this earlier question].
Otherwise, on Windows, see the response to link:#capprobwin[this
question] and, on a UNIX-flavored OS, see the response to
link:#capprobunix[this question].
=== Can Wireshark capture on (my T1/E1 line, SS7 links, etc.)?
Wireshark can only capture on devices supported by libpcap/Npcap. On
most OSes, only devices that can act as network interfaces of the type
that support IP are supported as capture devices for libpcap/Npcap,
although the device doesn't necessarily have to be running as an IP
interface in order to support traffic capture.
On Linux and FreeBSD, libpcap 0.8 and later support the API for
"Display filters in Wireshark are very powerful; more fields are
filterable in Wireshark than in other protocol analyzers, and the syntax
you can use to create your filters is richer. As Wireshark progresses,
expect more and more protocol fields to be allowed in display filters.
Packet capturing is performed with the pcap library. The capture filter
syntax follows the rules of the pcap library. This syntax is different
from the display filter syntax."
The capture filter syntax used by libpcap can be found in the
http://www.tcpdump.org/tcpdump_man.html[tcpdump(8)] man page.
=== How can I capture packets with CRC errors?
Wireshark can capture only the packets that the packet capture
library - libpcap on UNIX-flavored OSes, and the Npcap port to Windows
of libpcap on Windows - can capture, and libpcap/Npcap can capture only
the packets that the OS's raw packet capture mechanism (or the Npcap
driver, and the underlying OS networking code and network interface
drivers, on Windows) will allow it to capture.
Unless the OS always supplies packets with errors such as invalid CRCs
to the raw packet capture mechanism, or can be configured to do so,
invalid CRCs to the raw packet capture mechanism, Wireshark - and other
programs that capture raw packets, such as tcpdump - cannot capture
those packets. You will have to determine whether your OS needs to be so
configured and, if so, can be so configured, configure it if necessary
and possible, and make whatever changes to libpcap and the packet
capture program you're using are necessary, if any, to support capturing
those packets.
Most OSes probably do *not* support capturing packets with invalid CRCs
on Ethernet, and probably do not support it on most other link-layer
types. Some drivers on some OSes do support it, such as some Ethernet
drivers on FreeBSD; in those OSes, you might always get those packets,
or you might only get them if you capture in promiscuous mode (you'd
have to determine which is the case).
Note that libpcap does not currently supply to programs that use it an
indication of whether the packet's CRC was invalid (because the drivers
themselves do not supply that information to the raw packet capture
mechanism); therefore, Wireshark will not indicate which packets had CRC
errors unless the FCS was captured (see the next question) and you're
using Wireshark 0.9.15 and later, in which case Wireshark will check the
CRC and indicate whether it's correct or not.
=== How can I capture entire frames, including the FCS?
Wireshark can only capture data that the packet capture library -
libpcap on UNIX-flavored OSes, and the Npcap port to Windows of libpcap
on Windows - can capture, and libpcap/Npcap can capture only the data
that the OS's raw packet capture mechanism (or the Npcap driver, and the
underlying OS networking code and network interface drivers, on Windows)
will allow it to capture.
For any particular link-layer network type, unless the OS supplies the
FCS of a frame as part of the frame, or can be configured to do so,
Wireshark - and other programs that capture raw packets, such as tcpdump
- cannot capture the FCS of a frame. You will have to determine whether
your OS needs to be so configured and, if so, can be so configured,
configure it if necessary and possible, and make whatever changes to
libpcap and the packet capture program you're using are necessary, if
any, to support capturing the FCS of a frame.
Most OSes do *not* support capturing the FCS of a frame on Ethernet,
and probably do not support it on most other link-layer types. Some
drivres on some OSes do support it, such as some (all?) Ethernet drivers
on NetBSD and possibly the driver for Apple's gigabit Ethernet interface
in macOS; in those OSes, you might always get the FCS, or you might only
get the FCS if you capture in promiscuous mode (you'd have to determine
which is the case).
Versions of Wireshark prior to 0.9.15 will not treat an Ethernet FCS in
a captured packet as an FCS. 0.9.15 and later will attempt to determine
whether there's an FCS at the end of the frame and, if it thinks there
is, will display it as such, and will check whether it's the correct
CRC-32 value or not.
=== I'm capturing packets on a machine on a VLAN; why don't the packets I'm capturing have VLAN tags?
You might be capturing on what might be called a "VLAN interface" -
the way a particular OS makes VLANs plug into the networking stack
might, for example, be to have a network device object for the physical
interface, which takes VLAN packets, strips off the VLAN header and
constructs an Ethernet header, and passes that packet to an internal
network device object for the VLAN, which then passes the packets onto
various higher-level protocol implementations.
In order to see the raw Ethernet packets, rather than "de-VLANized"
packets, you would have to capture not on the virtual interface for the
VLAN, but on the interface corresponding to the physical network device,
if possible. See https://wiki.wireshark.org/CaptureSetup/VLAN[the
Wireshark Wiki item on VLAN capturing] for details.
=== Why does Wireshark hang after I stop a capture?
The most likely reason for this is that Wireshark is trying to look
up an IP address in the capture to convert it to a name (so that, for
example, it can display the name in the source address or destination
address columns), and that lookup process is taking a very long time.
Wireshark calls a routine in the OS of the machine on which it's
running to convert of IP addresses to the corresponding names. That
routine probably does one or more of:
* a search of a system file listing IP addresses and names;
* a lookup using DNS;
* on UNIX systems, a lookup using NIS;
* on Windows systems, a NetBIOS-over-TCP query.
If a DNS server that's used in an address lookup is not responding, the
lookup will fail, but will only fail after a timeout while the system
routine waits for a reply.
In addition, on Windows systems, if the DNS lookup of the address
fails, either because the server isn't responding or because there are
no records in the DNS that could be used to map the address to a name, a
NetBIOS-over-TCP query will be made. That query involves sending a
message to the NetBIOS-over-TCP name service on that machine, asking for
the name and other information about the machine. If the machine isn't
running software that responds to those queries - for example, many
non-Windows machines wouldn't be running that software - the lookup will
only fail after a timeout. Those timeouts can cause the lookup to take a
long time.
If you disable network address-to-name translation - for example, by
turning off the "Enable network name resolution" option in the "Capture
Options" dialog box for starting a network capture - the lookups of the
address won't be done, which may speed up the process of reading the
capture file after the capture is stopped. You can make that setting the
default by selecting "Preferences" from the "Edit" menu, turning off the
"Enable network name resolution" option in the "Name resolution" options
in the preferences disalog box, and using the "Save" button in that
dialog box; note that this will save _all_ your current preference
settings.
If Wireshark hangs when reading a capture even with network name
resolution turned off, there might, for example, be a bug in one of
Wireshark's dissectors for a protocol causing it to loop infinitely. If
you're not running the most recent release of Wireshark, you should
first upgrade to that release, as, if there's a bug of that sort, it
might've been fixed in a release after the one you're running. If the
hang occurs in the most recent release of Wireshark, the bug should be
reported to mailto:wireshark-dev@wireshark.org[the Wireshark developers'
mailing list] at `wireshark-dev@wireshark.org`.
On UNIX-flavored OSes, please try to force Wireshark to dump core, by
sending it a `SIGABRT` signal (usually signal 6) with the `kill`
command, and then get a stack trace if you have a debugger installed. A
stack trace can be obtained by using your debugger (`gdb` in this
example), the Wireshark binary, and the resulting core file. Here's an
example of how to use the gdb command `backtrace` to do so.
----
$ gdb wireshark core
(gdb) backtrace
..... prints the stack trace
(gdb) quit
$
----
The core dump file may be named "wireshark.core" rather than "core" on
some platforms (e.g., BSD systems).
Also, if at all possible, please send a copy of the capture file that
caused the problem. When capturing packets, Wireshark normally writes
captured packets to a temporary file, which will probably be in `/tmp`
or `/var/tmp` on UNIX-flavored OSes, `\TEMP` on the main system disk
(normally `\Documents and Settings\`your login name
`\Local Settings\Temp` on the main system disk on Windows Windows XP and
Server 2003, and `\Users\your login name\AppData\Local\Temp` on the main
system disk on Windows Vista and later, so the capture file will
probably be there. If you are capturing on a single interface, it will
have a name of the form,
`wireshark_<iface>_YYYYmmddHHMMSS_XXXXXX.<fmt>`, where <fmt> is the
capture file format (pcap or pcapng), and <iface> is the actual name of
the interface you are capturing on; otherwise, if you are capturing on
multiple interfaces, it will have a name of the form,
`wireshark_<N>_interfaces_YYYYmmddHHMMSS_XXXXXX.<fmt>`, where <N> is the
number of simultaneous interfaces you are capturing on. Please don't
send a trace file greater than 1 MB when compressed; instead, make it
available via FTP or HTTP, or say it's available but leave it up to a
developer to ask for it. If the trace file contains sensitive
information (e.g., passwords), then please do not send it.
== Capturing packets on Windows
[[capprobwin]]
=== I'm running Wireshark on Windows; why does some network interface on my machine not show up in the list of interfaces in the "Interface:" field in the dialog box popped up by "Capture->Start", and/or why does Wireshark give me an error if I try to capture on that interface?
Wireshark relies on the Npcap library, on the Npcap device driver,
and and on the facilities that come with the OS on which it's running in
order to do captures.
Therefore, if the OS, the Npcap library, or the Npcap driver don't
support capturing on a particular network interface device, Wireshark
won't be able to capture on that device.
If an interface doesn't show up in the list of interfaces in the
"Interface:" field, and you know the name of the interface, try entering
that name in the "Interface:" field and capturing on that device.
If the attempt to capture on it succeeds, the interface is somehow not
being reported by the mechanism Wireshark uses to get a list of
interfaces. Try listing the interfaces with WinDump; see
https://www.windump.org/[the WinDump Web site] for information on using
WinDump.
You would run WinDump with the `-D` flag; if it lists the interface,
lists to see if anybody happens to know about the problem and know a
workaround or fix for the problem. (Note that you will have to subscribe
to that list in order to be allowed to mail to it; see
https://nmap.org/npcap/[the Npcap support page] for information on the
mailing list.) In your mail, please give full details of the problem, as
described above, and also indicate that the problem occurs with WinDump,
not just with Wireshark.
=== I'm running Wireshark on Windows; why do no network interfaces show up in the list of interfaces in the "Interface:" field in the dialog box popped up by "Capture->Start"?
This is really link:#capprobwin[the same question as a previous one];
see the response to that question.
=== I'm running Wireshark on Windows; why am I not seeing any traffic being sent by the machine running Wireshark?
If you are running some form of VPN client software, it might be
causing this problem; people have seen this problem when they have Check
Point's VPN software installed on their machine. If that's the cause of
the problem, you will have to remove the VPN software in order to have
Wireshark (or any other application using Npcap) see outgoing packets;
unfortunately, neither we nor the Npcap developers know any way to make
Npcap and the VPN software work well together.
Also, some drivers for Windows (especially some wireless network
interface drivers) apparently do not, when running in promiscuous mode,
arrange that outgoing packets are delivered to the software that
requested that the interface run promiscuously; try turning promiscuous
mode off.
=== When I capture on Windows in promiscuous mode, I can see packets other than those sent to or from my machine; however, those packets show up with a "Short Frame" indication, unlike packets to or from my machine. What should I do to arrange that I see those packets in their entirety?
In at least some cases, this appears to be the result of PGPnet
running on the network interface on which you're capturing; turn it off
on that interface.
=== I'm trying to capture 802.11 traffic on Windows; why am I not seeing any packets?
At least some 802.11 card drivers on Windows appear not to see any
packets if they're running in promiscuous mode. Try turning promiscuous
mode off; you'll only be able to see packets sent by and received by
your machine, not third-party traffic, and it'll look like Ethernet
traffic and won't include any management or control frames, but that's a
list of cards supported with WinPcap] for information on support of
various adapters and drivers with WinPcap.
=== I'm trying to capture 802.11 traffic on Windows; why am I seeing packets received by the machine on which I'm capturing traffic, but not packets sent by that machine?
This appears to be another problem with promiscuous mode; try turning
it off.
=== I'm trying to capture Ethernet VLAN traffic on Windows, and I'm capturing on a "raw" Ethernet device rather than a "VLAN interface", so that I can see the VLAN headers; why am I seeing packets received by the machine on which I'm capturing traffic, but not packets sent by that machine?
The way the Windows networking code works probably means that packets
are sent on a "VLAN interface" rather than the "raw" device, so packets
sent by the machine will only be seen when you capture on the "VLAN
interface". If so, you will be unable to see outgoing packets when
capturing on the "raw" device, so you are stuck with a choice between
seeing VLAN headers and seeing outgoing packets.
== Capturing packets on UN*Xes
[[capprobunix]]
=== I'm running Wireshark on a UNIX-flavored OS; why does some network interface on my machine not show up in the list of interfaces in the "Interface:" field in the dialog box popped up by "Capture->Start", and/or why does Wireshark give me an error if I try to capture on that interface?
You may need to run Wireshark from an account with sufficient
privileges to capture packets, such as the super-user account, or may
need to give your account sufficient privileges to capture packets. Only
those interfaces that Wireshark can open for capturing show up in that
list; if you don't have sufficient privileges to capture on any
interfaces, no interfaces will show up in the list. See
mailing lists to see if anybody happens to know about the problem and
know a workaround or fix for the problem. In your mail, please give full
details of the problem, as described above, and also indicate that the
problem occurs with `tcpdump` not just with Wireshark.
=== I'm running Wireshark on a UNIX-flavored OS; why do no network interfaces show up in the list of interfaces in the "Interface:" field in the dialog box popped up by "Capture->Start"?
This is really link:#capprobunix[the same question as the previous
one]; see the response to that question.
=== I'm capturing packets on Linux; why do the time stamps have only 100ms resolution, rather than 1us resolution?
Wireshark gets time stamps from libpcap/Npcap, and libpcap/Npcap get
them from the OS kernel, so Wireshark - and any other program using
libpcap, such as tcpdump - is at the mercy of the time stamping code in
the OS for time stamps.
At least on x86-based machines, Linux can get high-resolution time
stamps on newer processors with the Time Stamp Counter (TSC) register;
for example, Intel x86 processors, starting with the Pentium Pro, and
including all x86 processors since then, have had a TSC, and other
vendors probably added the TSC at some point to their families of x86
processors. The Linux kernel must be configured with the CONFIG_X86_TSC
option enabled in order to use the TSC. Make sure this option is enabled
in your kernel.
In addition, some Linux distributions may have bugs in their versions
of the kernel that cause packets not to be given high-resolution time
stamps even if the TSC is enabled. See, for example, bug 61111 for Red
Hat Linux 7.2. If your distribution has a bug such as this, you may have
to run a standard kernel from kernel.org in order to get high-resolution
time stamps.
== Capturing packets on wireless LANs
=== How can I capture raw 802.11 frames, including non-data (management, beacon) frames?
That depends on the operating system on which you're running, and on
the 802.11 interface on which you're capturing.
This would probably require that you capture in promiscuous mode or in
the mode called "monitor mode" or "RFMON mode". On some platforms, or
with some cards, this might require that you capture in monitor mode -
promiscuous mode might not be sufficient. If you want to capture traffic
on networks other than the one with which you're associated, you will
have to capture in monitor mode.
Not all operating systems support capturing non-data packets and, even
on operating systems that do support it, not all drivers, and thus not
all interfaces, support it. Even on those that do, monitor mode might
not be supported by the operating system or by the drivers for all
interfaces.
*NOTE:* an interface running in monitor mode will, on most if not all
platforms, not be able to act as a regular network interface; putting it
into monitor mode will, in effect, take your machine off of whatever
network it's on as long as the interface is in monitor mode, allowing it
only to passively capture packets.
This means that you should disable name resolution when capturing in
monitor mode; otherwise, when Wireshark (or TShark, or tcpdump) tries to
display IP addresses as host names, it will probably block for a long
time trying to resolve the name because it will not be able to
communicate with any DNS or NIS servers.
See https://wiki.wireshark.org/CaptureSetup/WLAN[the Wireshark Wiki
item on 802.11 capturing] for details.
=== How do I capture on an 802.11 device in monitor mode?
Whether you will be able to capture in monitor mode depends on the
operating system, adapter, and driver you're using. See
link:#raw_80211_sniff[the previous question] for information on monitor
mode, including a link to the Wireshark Wiki page that gives details on
802.11 capturing.
== Viewing traffic
=== Why am I seeing lots of packets with incorrect TCP checksums?
If the packets that have incorrect TCP checksums are all being sent
by the machine on which Wireshark is running, this is probably because
the network interface on which you're capturing does TCP checksum
offloading. That means that the TCP checksum is added to the packet by
the network interface, not by the OS's TCP/IP stack; when capturing on
an interface, packets being sent by the host on which you're capturing
are directly handed to the capture interface by the OS, which means that
they are handed to the capture interface without a TCP checksum being
added to them.
The only way to prevent this from happening would be to disable TCP
checksum offloading, but
1. that might not even be possible on some OSes;
2. that could reduce networking performance significantly.
However, you can disable the check that Wireshark does of the TCP
checksum, so that it won't report any packets as having TCP checksum
errors, and so that it won't refuse to do TCP reassembly due to a packet
having an incorrect TCP checksum. That can be set as an Wireshark
preference by selecting "Preferences" from the "Edit" menu, opening up
the "Protocols" list in the left-hand pane of the "Preferences" dialog
box, selecting "TCP", from that list, turning off the "Check the
validity of the TCP checksum when possible" option, clicking "Save" if
you want to save that setting in your preference file, and clicking
"OK".
It can also be set on the Wireshark or TShark command line with a
`-o tcp.check_checksum:false` command-line flag, or manually set in your
preferences file by adding a `tcp.check_checksum:false` line.
=== I've just installed Wireshark, and the traffic on my local LAN is boring. Where can I find more interesting captures?
We have a collection of strange and exotic sample capture files at