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# System prepended metadata

title: B10902126 資工三 陳致翰 CN HW1

---

B10902126 資工三 陳致翰 CN HW1

### 1. 
```ref:黃千睿b10902068```
1.
(a)

![](https://hackmd.io/_uploads/HJ0-r2LeT.png)

(b)
According to my observation,the transmit rate limit is 264.5KBps/sec = 2116Kbps/sec.

2.
IP : 140.112.28.151
According to the observation of packets,I find that 140.112.28.151 occures frequently,which means it may be the local IP address.

3.
(a)418 I'm a teapot
(b)Baby shark, doo doo doo doo doo doo
According to my observation,tcp number of packets(7315) is less than UDP(28814).The main difference is that the transmission speed of UDP is faster than TCP,while it is relatively unreliable. So in the same inteveral time,there are more UDP packets than TCP packets.

4.
Method1 : IPv4 and IPv6 headers include a field call "IP version",which is 4-bits length.IPv4 has value 4->0100,IPv6 has value 6->0110
Method2 : IPv6 packets use the next header field to specify the type of the next header, including both extension headers and upper-layer protocols.While IPv4 packets have a protocol field in their header, which indicates TCP/UDP follows the IPv4 header.
![](https://hackmd.io/_uploads/B1DgGHtep.png)

![](https://hackmd.io/_uploads/rJveGStea.png)

ref : https://chat.openai.com/share/d7ef132d-4c39-45dd-b08a-53d631feb983

5.
(a)UDP payload(1357 bytes) .The packet include query for IP address of zh.wikipedia.org and get response from it.
(b)
A:It indicates it is IPv4 address.
CNAME:used to map one domain name to another
NS:Name server
(c)103.102.166.224

### 2.

1.
username : cnta
password : ji32k7au4a83

2.
(1) 5000
(2) 

|file | port | 
| -------- | -------- | 
| lorem.txt| 30012 | 
| links.txt| 30013    | 
| midterm.txt     | 30010     | 
| puppy.png    | 30016    | 

3.
(a) midterm.txt
(b) 10 questions

### 3.

1.
4000.The application of the protocal is TCP,typically use 25 port.

2.
sender : <prof.devil@notearuniv.edu>
reciever : <wanna.cry@notearuniv.edu>
subject : Signing up for the course

3.
Yes,he wanted to take "Assembly Languages from Beginner to Quitter".The permission code is "toRt0R-53d-@CcuM54n-bibenduM".

4.
No.Without TLS,it will cause several problems. It will lack of data encryption,the transmission between client and server is vulnerable. It will be easier to be attacked,attack will maliciously modify the file. It also affect data integrity,which can't keep data remaining unchanged during transmision without TLS.
### 4.
1.

![](https://hackmd.io/_uploads/HyrIxuBla.png)

2.

I can't find the packet with password.The difference of the two is that https://voip.csie.org:4072 use TLS(Transport Layer Security)  for encryption,which https://voip.csie.org:4070 doesn't have TLS after my observation.

### 5.
1.
command line:
```curl -X POST -d "username=b10902126&password=123" http://voip.csie.org:4071/submit```

![](https://hackmd.io/_uploads/H1bJ1TBgT.png)

![](https://hackmd.io/_uploads/By-kyTSep.png)

2.
command line:
```curl -X POST -d "username=b10902126&password=123&secret=CN" http://voip.csie.org:4071/submit```

![](https://hackmd.io/_uploads/SJMh1pSga.png)



### 6.

1.
Traceroute will send packets to the specified destination IP address with varying TTL(Time-to-alive) values.Packets travel through routers and record IP addresses,and then come back to the sorce and record time delay. By above method,it finds the path 8.8.8.8
![](https://hackmd.io/_uploads/SJdgZbdxT.png)

2.
There are lots of star symbol .It means the router can't get a response at that hop with a specific time limit. It may be caused due to routers block packets.
![](https://hackmd.io/_uploads/HkqxSb_ep.png)



### 7.
1.

IP : 140.112.30.26

![](https://hackmd.io/_uploads/HykMm3rep.png)

2.

IP : 52.94.236.248 / 54.239.28.85

![](https://hackmd.io/_uploads/BkaSEnrgT.png)

ans : There are many reasons for binding multiple addresses under a single domain.The main reasons are for load balance and availability. It won't let a server being overwhelmed by scheduling well,or when one server is crashed,workload can redirect to other servers.