AWS 延長 t4g.small 的 free trial

Plurk 上看到朋友貼的「Announcing Amazon EC2 T4g Free Trial Extension」。

t4g.small 的 free trial 延長到明年年底了:

The Amazon Elastic Compute Cloud (Amazon EC2) T4g instance Free Trial is extended to December 31, 2024. All new and existing AWS customers can utilize the free trial to automatically deduct up to 750 hours per month with the t4g.small instances through December 31, 2024. You can start building on Graviton-based instances for no charge with the T4g free trial, though charges may apply for surplus CPU credits. Refer to Amazon EC2 FAQs for more details on the free-trial.

這台算是還蠻好用的 ARM-based 主機,t4g.small 是 2 vCPU + 2GB RAM 的規格,如果是自己會 tune 的話已經可以做不少事情了,再加上 EC2 在前 12 個月的 t3.micro (2 vCPU + 1GB RAM) 免費,就已經可以玩不少東西了:

750 hours per month of Linux, RHEL, or SLES t2.micro or t3.micro instance dependent on region

Amazon RDS 推出 RDS Extended Support

AWSAmazon RDS 推出了 MySQL 5.7 與 PostgreSQL 11 的 RDS Extended Support 服務:「Your MySQL 5.7 and PostgreSQL 11 databases will be automatically enrolled into Amazon RDS Extended Support」。


基本上都到 2027Q1 左右,差不多再多支援三年。

另外表上的時間有些接不起來的地方,則是在 Note 的地方說明。

其中 MySQL 5.7 的部分分成兩塊,其中 RDS for MySQL 5.7 的部分是比較清楚的:原來的 RDS standard support 到 2024/02/29,後續從 2024/03/01 馬上接付費的 RDS Extended Support。

Aurora MySQL 2 的 RDS standard support 則是直接一路到 2024/10/31,然後 2024/11/01~2024/11/30 的 RDS Extended Support 不收費,從 2024/12/01 開始收費:

RDS Extended Support for Aurora MySQL 2 starts on November 1, 2024, but will not be charged until December 1, 2024. Between November 1 and November 30, all Aurora MySQL 2 clusters are covered under RDS Extended Support.

而 PostgreSQL 11 的部分都一樣 (RDS for PostgreSQL 11 與 Aurora PostgreSQL 11),原來的 RDS standard support 到 2024/02/29,而 2024/03/01~2024/03/31 的 RDS Extended Support 則是免費的,從 2024/04/01 開始收費:

RDS Extended Support for PostgreSQL 11 starts on March 1, 2024, but will not be charged until April 1, 2024. Between March 1 and March 31, all PostgreSQL 11 instances on Aurora and RDS are covered under RDS Extended Support.

然後費用的部分也查的到了,是用 vCPU-hour 計算的,四條產品線的價位在 us-east-1 的計價是相同的,前面兩年是 $0.1/vCPU/hr,而第三年是 $0.2/vCPU/hr。

由於 RDS 的機器最少是 2 vCPU,所以一台機器至少要多付 $0.2/hr 的費用,這個費用基本上會比 RDS 費用還貴。

這邊給個比較的數字,同樣在 us-east-1 上,2 vCPU + 8GB RAM 的 db.t4g.large 要 $0.129/hr,而一樣 2 vCPU + 8GB RAM 如果是 db.m7g.large 則是 $0.168/hr,都還沒有 RDS Extended Support 貴;要到 r7g.large 這種以記憶體導向的 $0.1071/hr 才差不多跟上一樣的價錢。

另外一個方法應該就是改成自己在 EC2 上架設?這樣成本會因為 RDS 轉 EC2 的下降,整體大約會降到 1/4...


讓 git blame 可以忽略掉某些 restyle/reformat 的 commit

在 X (Twitter) 上看到這則推,提到了可以讓 git blame 自動忽略掉某些 restyle 或是 reformat 的 commit:

查了一下是在 2019 年八月出的 2.23.0 引入的,從 Documentation/RelNotes/2.23.0.txt 可以看到說明:

 * "git blame" learned to "ignore" commits in the history, whose
   effects (as well as their presence) get ignored.

除了可以在專案內單獨設定外,也可以在 ~/.gitconfig 內設定:

    ignoreRevsFile = .git-blame-ignore-revs

我是拿 rss-bridge 裡的 bridges/ARDMediathekBridge.php 測試,可以看到這個檔案最後的修改是「Reformat codebase v4」這包,也就是被放進 ignore 清單的 commit。

這個 commit 中,對 ARDMediathekBridge.php 這個檔案的 diff 則可以在「這裡」看到。

從 diff log 可以看到幾乎是所有的縮排都被改變了,但 GitHub 上面的 Blame 資訊,以及拉下來後用 git blame 或是 tig blame 可以注意到大多數有意義的地方都有被找出來「還原」,只有很簡單的內容沒有被辨識出來 (像是整行只有 /* 或是 { 之類的地方)。

看起來還是蠻有用的,先丟進 dotfiles 裡面了...

SMTP Smuggling 的安全漏洞 (LF 的問題),以及 Postfix 被無視的問題

Hacker News 上看到「SMTP Smuggling – Spoofing Email Worldwide (」這個攻擊,原文在「SMTP Smuggling - Spoofing E-Mails Worldwide」。

開頭的圖片把大方向解釋出來了,這是利用不同的 SMTP server 實作上對怎麼結束 DATA 的處理方式不同,這個問題會出現在兩組 SMTP server 丟信件時:

更細節的說,是遇到對於非 \r\n.\r\n (非 CRLF) 的處理方式不同時,就會產生出可以攻擊的空間:

這樣的攻擊因為可以偽造所有的 header,加上內部 SMTP server 在 IP 層看不到實際的 IP,就可以讓攻擊者完全繞過 SPF 檢查的部分。

從 SMTP 規格說起,在 SMTP 規格上都是用 \r\n (CRLF) 當作換行,這點從 1982 年 (41 年前) 已經 obsoleted 的 RFC 821 可以看到裡面全部都是使用 \r\n 當作換行。

後來更新的 RFC 2821 (2001,也已經 obsoleted) 與 RFC 5321 (2008,目前的標準) 則是除了描述 \r\n.\r\n 外,有提到禁止把 \n.\n 當作 DATA 的結尾辨識:

In particular, the sequence "<LF>.<LF>" (bare line feeds, without carriage returns) MUST NOT be treated as equivalent to <CRLF>.<CRLF> as the end of mail data indication.

但除了被禁止的 \n.\n 外,這次的攻擊用了其他的排列組合嘗試。

在 GMX、Ionos 以及 Microsoft Exchange Online 的 SMTP server 上發現都吃 \n.\r\n

However, as already mentioned, SMTP smuggling doesn't work for every receiving inbound SMTP server and, in this case, requires inbound SMTP servers to accept <LF>.<CR><LF> as end-of-data sequence.

Same as GMX and Ionos, Exchange Online allowed smuggling via a <LF>.<CR><LF> end-of-data sequence as well, which makes it possible to smuggle from every domain pointing their SPF record to Exchange Online.

而 Cisco Secure Email (Cloud) Gateway 支援 \r.\r

By default, Cisco Secure Email (Cloud) Gateway accepts . as end-of-data sequence, which does not get filtered by the following SMTP servers when sending outbound:

另外看了一下 Postfix 這邊的情況,可以看到「SMTP Smuggling」這份資料,裡面可以看到 Postfix 因為預設支援 \n.\r\n 也受到影響:

One different email service B that does support broken line endings in SMTP such as in <LF>.<CR><LF>.

Postfix is an example of email service B.

然後可以看到作者 Wietse Venema 直接在業面上公開點名 SEC Consult (這次安全漏洞的發現者) 沒有先聯絡的問題:

Unfortunately, criticial information provided by the researcher was not passed on to Postfix maintainers before publication of the attack, otherwise we would certainly have convinced SEC Consult to change their time schedule until after people had a chance to update their Postfix systems.

在 Postfix 的 e-mail 公告「[pfx-ann] SMTP Smuggling, workarounds and fix」裡面講的更硬 (non-responsible disclosure process):

As part of a non-responsible disclosure process, SEC Consult has published an email spoofing attack that involves a composition of email services with specific differences in the way they handle line endings other than <CR><LF>.

從最早的 snapshot (20231218105045 這份) 可以確認他們有發現 Postfix 的問題,但 timeline 上沒有接觸 Postfix 的團隊。

後續的更新把溝通問題推給了 CERTVINCE platform

As documented in the timeline of the blog post, the vulnerabilities were initially identified in June 2023 and after further internal research we contacted the specific, affected vendors (Microsoft, Cisco, GMX/Ionos). GMX and Microsoft fixed the issues promptly. But after receiving some feedback from Cisco, that our identified vulnerability is just a feature of the software and not a bug/vulnerability, we contacted CERT/CC on 17th August to get some help for further discussion with Cisco and involve other potentially affected vendors (such as sendmail) through the VINCE communication platform.

現在 community 這邊則是在醞釀提議取消他們在 37c3 上面的 talk:「」。

Beeper 宣佈新的手機號碼註冊方式,另外後續應該不會再更新了

Beeper 連續兩篇更新:「iMessage and Phone Registration Are Back - Kinda」、「Beeper - Moving Forward」。

第一篇提到新的手機號碼註冊方式,需要用舊的 iPhone 手機 jailbreak (iPhone 6iPhone X):

📱 Have an old iPhone (6/6s/SE1/7/8/X) and a Mac or Linux computer (Raspberry Pi works) - you’re in luck! Follow our instructions (takes only 10-15 minutes) to jailbreak your iPhone, install a Beeper tool to generate iMessage registration code, then update to the latest Beeper Mini app and enter your code. Phone number registration will now work! Leave the iPhone plugged into power, at home, connected to wifi.

從「How To - Register Phone Number With iMessage」可以看到是用 jailbreak 的方式取得對應的 token (code) 再丟進 Beeper Mini:


As much as we want to fight for what we believe is a fantastic product that really should exist, the truth is that we can’t win a cat-and-mouse game with the largest company on earth.

然後後續會把力氣放到新的 IM 開發:

In the new year, we’re shifting focus back to our long-term goal of building the best chat app on earth.


arXiv 提供 HTML 版本介面 (beta 版)

Hacker News 上看到「ArXiv now offers papers in HTML format (」這則,arXiv 推出了 beta 版的 HTML 介面:「Accessibility update: arXiv now offers papers in HTML format」。

不是每一篇都有上,需要是最近用 TeX 類格式上傳的才會轉:

We are happy to announce that as of Monday, December 18th, arXiv is now generating an HTML formatted version of all papers submitted in TeX/LaTeX (as long as papers were submitted on or after December 1st, 2023 and HTML conversion is successful – more on this below).

所以我先找了二十年前 Poincaré conjecture (龐加萊猜想) 的三篇論文,就沒有 HTML 版本:「The entropy formula for the Ricci flow and its geometric applications」、「Ricci flow with surgery on three-manifolds」、「Finite extinction time for the solutions to the Ricci flow on certain three-manifolds」。

Hacker News 的 comment 裡面有人給了有 HTML 版本的論文:「The detectability of single spinless stellar-mass black holes through gravitational lensing of gravitational waves with advanced LIGO」,以 render 的效果看起來還不錯?

另外這個站目前看起來沒有在 Fastly 上:

;; ANSWER SECTION:       300     IN      A

應該等成熟進 GA 時會把所有 TeX 檔案都轉出來?

arXiv 上了 Fastly CDN

看到 arXiv 宣佈上了 FastlyCDN:「Faster arXiv with Fastly」。

翻了一下 的 DNS record,可以看到現在是這樣:

;; ANSWER SECTION:              10      IN      A              10      IN      A              10      IN      A              10      IN      A

mtr 測試,看起來 HiNet 過去的 routing 還是進到新加坡。

不過 是在 CloudFront 上:

;; ANSWER SECTION:       3600    IN      CNAME 60 IN      A 60 IN      A 60 IN      A 60 IN      A

依照官方的說明看起來還在換,只是不知道已經在 CloudFront 上的 (像是上面提到的 會不會換過去:

That includes our home page, listings, abstracts, and papers — both PDF and HTML (more on that soon). 的 DNS 出包

Hacker News Daily 上的「Tell HN: added to their DNS record」這邊看到的,看起來是某種 misconfiguration 造成 microsoft.comA record 除了給正常的 IPv4 address 外,還給出了 的 IPv4 address。

不過裡面比較有趣的是 id=38704301 這個,提到他反而查不到,看 log 發現被 dnsmasq 認定是 DNS rebinding 的攻擊而擋下來不回應任何 IP address:

I was getting an empty answer for Turns out my dnsmasq is blocking it:

  $ dig | grep EDE
  ; EDE: 15 (Blocked)

  resolver.log:Dec 20 00:43:57 router dnsmasq[8172]: possible DNS-rebind attack detected:

翻了 dnsmasq 的 manpage,可以看到這個功能:


Reject (and log) addresses from upstream nameservers which are in the private ranges. This blocks an attack where a browser behind a firewall is used to probe machines on the local network. For IPv6, the private range covers the IPv4-mapped addresses in private space plus all link-local (LL) and site-local (ULA) addresses.

id=38704159 這邊也有類似的情況,不過這邊是提到 OpenWrt is currently IPv6-only on my network, because OpenWrt's DNS rebinding protection filters out the A records:

  $ ping -4
  ping: Address family for hostname not supported

  $ ping -6
  PING (2603:1030:c02:8::14)) 56 data bytes
  64 bytes from 2603:1030:c02:8::14 (2603:1030:c02:8::14): icmp_seq=1 ttl=112 time=68.4 ms

輸出 7.5V 的 USB Type A 頭

Hacker News Daily 上看到的:「My cat water fountain comes with a spicy USB power adapter (」,原文在「My cat water fountain comes with a spicy USB power adapter」。

作者的貓咪飲水噴泉用的是 USB Type A 的頭供電:

但仔細看會發現是特規,輸出 7.5V:


Ship of Theseus 條目的趣事

Hacker News Daily 上看到「0% of the phrases of the original Wikipedia "Ship of Theseus" article remain (」這篇,引用的是這則 tweet:

一開始掃過「Ship of Theseus」這個條目還沒有感覺,想偷懶發現有中文版的條目「忒修斯之船」:


回到原來的 tweet 上看才笑了出來。