Skip to main content

Wireshark

Capture Filters

MAC address OUI

Source

# haven't figured this capture filter out yet... display filter is easy...

bootp and dhcp

Source

port 67 or port 68

Name resolution protocols

DNS

Cisco Discovery Protocol

udp port 53

mDNS

udp port 5353

LLMNR

Link-local multicast name resolution

udp port 5355

All together now

udp port 53 or udp port 5353 or udp port 5355

Network discovery protocols

An easy way to view discovery protocol traffic from a laptop is by using Wireshark and the capture filters below for CDP, LLDP and MNDP. Use the appropriate capture filter for the type of device you're trying to gather information about, or use all three of them in the same capture filter.

CDP

Cisco Discovery Protocol

ether host 01:00:0c:cc:cc:cc and ether[16:4] = 0x0300000C and ether[20:2] == 0x2000

LLDP

ether proto 0x88cc

MNDP

Mikrotik Discovery Protocol

udp dst port 5678 and udp src port 5678

CDP/LLDP/MNDP

All three of the above capture filters in one:

(ether host 01:00:0c:cc:cc:cc and ether[16:4] = 0x0300000C and ether[20:2] == 0x2000) or (ether proto 0x88cc) or (udp dst port 5678 and udp src port 5678)

Capturing on an interval in Linux

The command below will capture all traffic to/from 8.8.8.8. A new capture file will be created every 600 seconds (10 minutes).

dumpcap -b duration:600 -f "host 8.8.8.8" -w capture-google

Mikrotik Packet Capture Streaming

To accept only TZSP traffic, Capture Filter like this can be used:

udp port 37008

Note that TZSP can be sent on any UDP port you set it to, so adjust the above capture as needed.

Using tshark

Interface List

This is typically needed when running tshark on Windows.

tshark -D
thsark -i <interface_id>

Capture Filter

# capture only udp dns packets
tshark -f "udp port 53"

Saving Packets

# save packets (doesn't display packets)
tsharp -f "udp port 37008" -w captured.pcap

# save and display packets
tsharp -f "udp port 37008" -w captured.pcap -P

# save and display packets with LOTS of detail
tsharp -f "udp port 37008" -w captured.pcap -P -O dns -V

Automatic stop

Options are duration:[seconds], filesize:[KB], and files:[n].

tshark -a duration:60
tshark -a filesize:1000

Ring Buffer Capture

tshark -b duration:3600 -b filesize:1000 -b files:24 -w ring_buffer.pcap
tshark -b duration:86400 -b filesize:1000 -b files:30 -w ring_buffer.pcap

Practical examples

# TZSP stream capture on specific interface
tshark -f "udp port 37008" -i 5

# TZSP stream capture on alternate udp port, uses decode as feature
tshark -f "udp port 37091" -d udp.port==37091,tzsp
Back to top