Hi All,
How does etherip work?
Lets say now that Host 1 sends a packet to Host 2 over the etherip tunnel (btw, they are on seperate LANs), how is the packet built and what does it look like?
Lets say a normal IP packet like the below :-
Frame 9 (614 on wire, 614 captured)
Arrival Time: Apr 10, 2003 20:44:41.831144000
Time delta from previous packet: 0.003858000 seconds
Time relative to first packet: 3.298858000 seconds
Frame Number: 9
Packet Length: 614 bytes
Capture Length: 614 bytes
Ethernet II
Destination: 00:08:02:53:01:a5 (SPLPW236206)
Source: 00:10:f6:a8:18:00 (Cisco_a8:18:00)
Type: IP (0x0800)
Internet Protocol, Src Addr: 192.168.69.1 (192.168.69.1), Dst Addr: SPLPW236206 (192.168.69.100)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0xc0 (DSCP 0x30: Class Selector 6; ECN: 0x00)
1100 00.. = Differentiated Services Codepoint: Class Selector 6 (0x30)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 600
Identification: 0x0002
Flags: 0x00
.0.. = Don't fragment: Not set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 255
Protocol: TCP (0x06)
Header checksum: 0xad27 (correct)
Source: 192.168.69.1 (192.168.69.1)
Destination: SPLPW236206 (192.168.69.100)
Transmission Control Protocol, Src Port: telnet (23), Dst Port: 2416 (2416), Seq: 2889137939, Ack: 1790722200, Len: 560
Source port: telnet (23)
Destination port: 2416 (2416)
Sequence number: 2889137939
Next sequence number: 2889138499
Acknowledgement number: 1790722200
Header length: 20 bytes
Flags: 0x0010 (ACK)
0... .... = Congestion Window Reduced (CWR): Not set
.0.. .... = ECN-Echo: Not set
..0. .... = Urgent: Not set
...1 .... = Acknowledgment: Set
.... 0... = Push: Not set
.... .0.. = Reset: Not set
.... ..0. = Syn: Not set
.... ...0 = Fin: Not set
Window size: 4128
Checksum: 0xc63c (correct)
Telnet
Data: \r\n
Data: \r\n
Data: Arsenal are the best team in the World
Now, if it was encap'd in etherip, would it take the entire packet, and put another IP header on it AND new ethernet header?
Does anyone have an etherip packet decode I can look at or a good dosument to show exactly what happens?
Many thx indeed,
Ken
