STUN stands for
Session
Traversal
Utilities for
NAT mainly used in NAT Traversal for IP Applications (say Voice, Video, Messaging).
Below snapshot shows STUN Request Packet
Below snapshot shows STUN Response Packet
Text view of full capture
Request
No. Time Source Destination Protocol Length Info
264 200.289545 10.0.0.2 77.72.169.158 CLASSIC-STUN 62 Message: Binding Request
Frame 264: 62 bytes on wire (496 bits), 62 bytes captured (496 bits)
Arrival Time: Aug 23, 2012 16:36:32.609220000 India Standard Time
Epoch Time: 1345719992.609220000 seconds
[Time delta from previous captured frame: 7.022449000 seconds]
[Time delta from previous displayed frame: 15.027355000 seconds]
[Time since reference or first frame: 200.289545000 seconds]
Frame Number: 264
Frame Length: 62 bytes (496 bits)
Capture Length: 62 bytes (496 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ip:udp:classicstun]
[Coloring Rule Name: UDP]
[Coloring Rule String: udp]
Ethernet II, Src: Vmware_ef:18:30 (00:0c:29:ef:18:30), Dst: (00:bb:f7:00:8b:1f)
Destination: (00:bb:f7:00:8b:1f)
Address: (00:bb:f7:00:8b:1f)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
Source: Vmware_ef:18:30 (00:0c:29:ef:18:30)
Address: Vmware_ef:18:30 (00:0c:29:ef:18:30)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
Type: IP (0x0800)
Internet Protocol Version 4, Src: 10.0.0.2 (10.0.0.2), Dst: 77.72.169.158 (77.72.169.158)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00: Not-ECT (Not ECN-Capable Transport))
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00)
Total Length: 48
Identification: 0x3eea (16106)
Flags: 0x00
0... .... = Reserved bit: Not set
.0.. .... = Don't fragment: Not set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 128
Protocol: UDP (17)
Header checksum: 0xfaea [correct]
[Good: True]
[Bad: False]
Source: 10.0.0.2 (10.0.0.2)
Destination: 77.72.169.158 (77.72.169.158)
User Datagram Protocol, Src Port: 8006 (8006), Dst Port: stun (3478)
Source port: 8006 (8006)
Destination port: stun (3478)
Length: 28
Checksum: 0x1f88 [validation disabled]
[Good Checksum: False]
[Bad Checksum: False]
Simple Traversal of UDP Through NAT
[Response In: 265]
Message Type: Binding Request (0x0001)
Message Length: 0x0000
Message Transaction ID: 000000007e5634120000000000000000
Response
No. Time Source Destination Protocol Length Info
265 200.465322 77.72.169.158 10.0.0.2 CLASSIC-STUN 98 Message: Binding Response
Frame 265: 98 bytes on wire (784 bits), 98 bytes captured (784 bits)
Arrival Time: Aug 23, 2012 16:36:32.784997000 India Standard Time
Epoch Time: 1345719992.784997000 seconds
[Time delta from previous captured frame: 0.175777000 seconds]
[Time delta from previous displayed frame: 0.175777000 seconds]
[Time since reference or first frame: 200.465322000 seconds]
Frame Number: 265
Frame Length: 98 bytes (784 bits)
Capture Length: 98 bytes (784 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ip:udp:classicstun]
[Coloring Rule Name: UDP]
[Coloring Rule String: udp]
Ethernet II, Src: (00:bb:f7:00:8b:1f), Dst: Vmware_ef:18:30 (00:0c:29:ef:18:30)
Destination: Vmware_ef:18:30 (00:0c:29:ef:18:30)
Address: Vmware_ef:18:30 (00:0c:29:ef:18:30)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
Source: (00:bb:f7:00:8b:1f)
Address: (00:bb:f7:00:8b:1f)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
Type: IP (0x0800)
Internet Protocol Version 4, Src: 77.72.169.158 (77.72.169.158), Dst: 10.0.0.2 (10.0.0.2)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00: Not-ECT (Not ECN-Capable Transport))
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00)
Total Length: 84
Identification: 0x19c5 (6597)
Flags: 0x02 (Don't Fragment)
0... .... = Reserved bit: Not set
.1.. .... = Don't fragment: Set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 238
Protocol: UDP (17)
Header checksum: 0x71eb [correct]
[Good: True]
[Bad: False]
Source: 77.72.169.158 (77.72.169.158)
Destination: 10.0.0.2 (10.0.0.2)
User Datagram Protocol, Src Port: stun (3478), Dst Port: 8006 (8006)
Source port: stun (3478)
Destination port: 8006 (8006)
Length: 64
Checksum: 0xac24 [validation disabled]
[Good Checksum: False]
[Bad Checksum: False]
Simple Traversal of UDP Through NAT
[Request In: 264]
[Time: 0.175777000 seconds]
Message Type: Binding Response (0x0101)
Message Length: 0x0024
Message Transaction ID: 000000007e5634120000000000000000
Attributes
Attribute: MAPPED-ADDRESS
Attribute Type: MAPPED-ADDRESS (0x0001)
Attribute Length: 8
Protocol Family: IPv4 (0x0001)
Port: 8006
IP: 61.12.12.132 (61.12.12.132)
Attribute: SOURCE-ADDRESS
Attribute Type: SOURCE-ADDRESS (0x0004)
Attribute Length: 8
Protocol Family: IPv4 (0x0001)
Port: 3478
IP: 77.72.169.158 (77.72.169.158)
Attribute: CHANGED-ADDRESS
Attribute Type: CHANGED-ADDRESS (0x0005)
Attribute Length: 8
Protocol Family: IPv4 (0x0001)
Port: 3479
IP: 77.72.169.159 (77.72.169.159)
Other articles of your interest might be
http://darshanams.blogspot.in/2012/06/sip-security1-scanning-voippbx-servers.html
http://darshanams.blogspot.in/2008/11/deciphering-google-talk-jabber.html
http://darshanams.blogspot.in/2009/03/i-was-just-checking-my-mails.html