Useful Git command

### 1. Fetch all remote branches ```shell git fetch origin ``` ### 2. Pull update to local branch ```bash git pull origin main --rebase --autostash ``` ### 3. Rebase other branch to main branch ```bash # checkout to main branch git checkout main git rebase xxx ``` ### 4. Show branchs ``` bash # show local branch git branch # show remote branch git branch -a ``` ### 5. Create branch ``` bash git branch ``` ### 6. Switch branch ``` bash git checkout ``` ### 7. Commit code change ``` bash # In one line. git commit -m # Add commit message from file git commit -F # Edit commit message with editor git commit -a ``` ### 8. Revert ``` bash #Reset git reset HEAD # 還原 "指定" 的檔案狀態 git reset HEAD # 還原 "全部" 的檔案狀態 #Checkout git checkout -- # 還原 "指定" 的檔案狀態 git checkout # 還原 "全部" 的檔案狀態 ``` ### 9. Compare ``` bash # compare difference git diff # show difference file git status ``` ### 10. Push ``` bash # first time git push -u origin # normal git push # force git push -f ```

Append ccflag in yocto bbfile

Could append ccfllag with define flag which wanna to append like following ```bash # CFLAGS_append_{actived_machine_name} = "-DHT_QCA_WIFI " CFLAGS_append_chita-clr = "-DHT_QCA_WIFI " ```

【拆雷實錄】fragmeted IP 封包追蹤

最近在Trace fragmeted IP 封包無法被原本程式加的rule "-A INPUT -f -j DROP"阻擋，原因是他是加在input表，其優先權是低於raw表，順序是在defrag之後，這時被切割的packet已經經過defrag重組完，所以無法match fragmented的flag，所以按下面這篇文章需要將rule加在raw表，因為raw表的優先權比defrag高。 [https://blog.csdn.net/caofengtao1314/article/details/120047179](https://blog.csdn.net/caofengtao1314/article/details/120047179) 更改過的rule指令會像是這樣 ```bash iptables -t raw -I PREROUTING -i erouter0 -f -j DROP # 打LOG方便追蹤 iptables -t raw -I PREROUTING -i erouter0 -f -j LOG --log-prefix "[ATK] IP fragmented" --log-level 1 ``` 理論上改成這樣就OK，但在比較後面的kernel版本變得比較複雜，defrag變得比raw表的優先權高，變成就算把上面的rule加到raw表也檔不住，所以按下面這篇文章說明需要在load iptable_raw時傳遞參數 ```bash modprobe iptable_raw raw_before_defrag=1 ``` [https://serverfault.com/questions/964072/how-to-block-incoming-ipv6-fragments](https://serverfault.com/questions/964072/how-to-block-incoming-ipv6-fragments) 而如果是builtin的kernel module，則需要透過Bootloadert傳遞參數或定義Kernel command line(CONFIG_CMDLINE)在Kernel config，在我的情況是第二種builtin的kernel module，然後在不更改Bootloader的前提，所以我需要加Kernel command line ```ini CONFIG_CMDLINE_BOOL=y CONFIG_CMDLINE="raw_before_defrag=1" ```

【拆雷實錄】ping 8.8.8.8 data length問題

最近遇到busybox ping 8.8.8.8的怪問題，當ping的data length > 88就ping不通，後面根據google的一篇文章，修改unpack function，拿掉datalen的檢查就OK了。 ## 程式碼 [https://gist.github.com/JeffTsengTwn/439e7660958709b388c9cc7eeabc21fb#file-ping-c](https://gist.github.com/JeffTsengTwn/439e7660958709b388c9cc7eeabc21fb#file-ping-c)