---
title: Lab Meeting Minutes 2023/02/14
tags: lab_meeting
---
> Outline
> [TOC]
---
# PERAL Lab Meeting
- 時間：112 年 02 月 14 日 10:00
- 地點：線上
- 線上會議連結 : [Online](https://meet.google.com/ypn-puou-dny)
- 出席者：吳坤熹老師、謝萬霖、吳騰然、劉怡君、田蕙瑜、洪胤勛、丘世宇、莊才賢、劉冠伶、林大智
- 請假: 紀見如、繆亭霄

- 會議主題：[The Use of Extension Headers in IPv6 for Network Steganography and Its Dilemma](https://docs.google.com/presentation/d/1oGSSjBTqdLGX0IXNFb8bju3q0a_i2sLxZohmvPNAT0o/edit?usp=sharing)
- 主講者: 劉怡君
- 主記: 田蕙瑜

## 會議內容
- IPv6 EH
>
* Type
- Hop-by-hop
-
- Dst
- usually in mobile ipv6
- Routing
-
- Frag.
- ipv6 router will not deal with frag., it should be grag in source
- Example

- Dilemma of IPv6 Packets Having Extension Headers
> What is the delemma of hiding data in IPv6 EH
- While sending by DST EH,
- the byte of EH more

- In Phoebe's case
- In Ubuntu, while more than 4-byte the drop rate will higher than 90%(?)
---

### 建議&問題
1. IPv4 Option 的缺點講得太簡略了，等於沒講。原本不懂的人還是不懂。[name=Solomon]

2. Drop rate 那麼高，它有沒有提出甚麼改善的方法？[name=Lawrance]
Ans: 其實這篇 paper 是分析，分析的結果是建議不要把內容放在 EH。[name=Pheobe]

3. 想請 pheobe 再更詳細的說明 ipv4 option 的內容以及它的缺點 [name=Ashley]
Ans:
- 
- Red field was drop by IPv6
- Yellow field name remains the same between IPv4 and IPv6
- Blue field means making some change from IPv4 to IPv6
- e.g. Time to Live :arrow_right: Hop Limit

3. Removing IPv4 Options is only one step in improving the performance of IP packets processing. Removing "Header Checksum" is another step. Long time ago, when the transmission speed is only 300bps, people's effort is improving the transmission rate. Now we are transferring over fibers, so people want to improve the processing speed of routers. [name=Solomon]

4. 注意勿自打嘴巴，削弱說服力。e.g. "The speed of current network devices is fast so it may not make great difference" [name=Solomon]

5. What is PadN? [name=Branko]
Ans: Padding works as alignment in packet header/EH. Pad1 means add 1-byte; PadN means add more than one byte in header.

6. [name=Choffin]
Ans: IPv6 with extension option looks SUS, router usually drop them. As the result, IPv6 Extension header will look generic if you pass them during a service (e.g. DNS Request).

7. p.7 會有一些 header 超過 8 個 bits 嗎？ [name=Jerry]
Ans: Router will take care of sigle packet with PadN

8. If use IPv6, is there a limit of record route extension header compared with IPV4?[name=Jerry]
Ans:

9. The len of padding usually in 0-7, so it is common that unusual PadN(more than 7) will be droped. Why u claimed that EH is easy to drop so EH is not recommended to use? [name=Solomon]
Ans: In following test, there is other option from [IANA](https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml) used in test and perform better than PadN.

10. Where is the experiment in paper done? [name=Angela]
Ans:

11. Follow the Q10, to be more specific, Packet 是被中間的 router drop or dropped by dst device? [name=Solomon]
Ans: 無法判斷從哪被 Drop 掉，只能從 Dst 觀測。

12. 如果實驗環境限制在台灣學術網路，有辦法觀測封包在哪裡被丟棄嗎 (To Be Check) [name=Solomon]
- This should be a potential research topic.

13. p.2 Recommend change to the picture of IPv6 vs IPv4, that will better to follow [name=Toby]
14. When will PadN be used? [name=Edgar]
Ans: If header is not aligned, it will auto pad.

15. What is PadN, specially in normal packet? [name=Edgar]
Ans: 我沒有抓過一般EH，所以待補

## 待追蹤事項
1. 觀測 packet 是 dropped by router or dst [name=Solomon]
- If packets was router, your expriment will be hard to do.
2. 釐清 Geoff 結論 [name=Solomon]

## 臨時動議
1. 下週 Meeting 暫停一次
2. 開學後 Meeting 時間為週五早上 9 點到 11 點，因此下一次的 Meeting 日期為 3/3。
3. 228 連假老師想約大家運動+聚餐，目前投票的結果最高票是 2/25 禮拜六下午 2 點。

---
散會結束時間： 11:23