Home » Posts tagged "public"

保護 TLS 的 Hostname

看到「Encrypted Server Name Indication for TLS 1.3」這個,由 FastlyCloudflareApple 的人聯手推出的 draft,想要保護 TLS 連線一開始明文傳輸的 hostname 部分。看起來是透過 DNS 發佈 public key,然後使用者用這把 public key 保護 hostname 的部分...

而 DNS 的部分可以透過 DNS over TLS 或是 DNS over HTTPS 來保護,這樣讓 ISP 沒有任何資訊可以看到 hostname,把暴露的資訊再降低...

來繼續關注這個技術...

Cloudflare 推出 Argo Tunnel

Cloudflare 推出了 Argo Tunnel,可以將內部網路與 Cloudflare 之間打通:「Argo Tunnel: A Private Link to the Public Internet」。

Cloudflare 在去年推出了 Wrap (可以參考「Cloudflare 推出的 Wrap 讓你不用在本地端開對外的 Port 80/443」這篇),這次其實只是改名:

During the beta period, Argo Tunnel went under a different name: Warp. While we liked Warp as a name, as soon as we realized that it made sense to bundle Warp with Argo, we wanted it to be under the Argo product name. Plus, a tunnel is what the product is so it's more descriptive.

看起來沒有什麼新的玩意... 純粹改名字 :o

Cloudflare 推出 1.1.1.1 的 DNS Resolver 服務

Cloudflare 推出了 1.1.1.1 上的 DNS Resolver 服務:「Announcing 1.1.1.1: the fastest, privacy-first consumer DNS service」,主打項目是隱私以及效能。

然後因為這個 IP 的特殊性,上面有不少奇怪的流量... 而 Cloudflare 跟 APNIC 交換條件後取得這個 IP address 的使用權 (然後 anycast 發出去):

APNIC's research group held the IP addresses 1.1.1.1 and 1.0.0.1. While the addresses were valid, so many people had entered them into various random systems that they were continuously overwhelmed by a flood of garbage traffic. APNIC wanted to study this garbage traffic but any time they'd tried to announce the IPs, the flood would overwhelm any conventional network.

We talked to the APNIC team about how we wanted to create a privacy-first, extremely fast DNS system. They thought it was a laudable goal. We offered Cloudflare's network to receive and study the garbage traffic in exchange for being able to offer a DNS resolver on the memorable IPs. And, with that, 1.1.1.1 was born.

Cloudflare 做了效能比較表 (與 Google Public DNSOpenDNS 比較),可以看到平均速度快不少:

在台灣的話,HiNet 非固定制 (也就是 PPPoE 連線的使用者) 連到 8.8.8.8 有奇怪的 latency:

可以比較同一台機器對 168.95.1.1 的反應速度:

不過如果你是 HiNet 固定制 (固 2 或是固 6 IP 那種,不透過 PPPoE,直接設定 IP address 使用 bridge mode 連線的使用者),兩者的 latency 就差不多,不知道是 Google 還是 HiNet 的架構造成的。

另外比較奇怪的一點是在文章最後面提到的 https://1.1.1.1/,理論上不會發 IP-based 的 SSL certificate 才對?不知道 CEO 老大是有什麼誤解... XD

Visit https://1.1.1.1/ from any device to get started with the Internet's fastest, privacy-first DNS service.

Update:查了資料發現是可以發的,只是大多數的 CA 沒有提供而已...

Slack 推出 Private Shared Channel,在兩個團體中間開 Private Channel

Slack 推出的新功能 Private Shared Channel:「Private shared channels are now available」,當然,這是付費功能 XD

Shared channels (beta) are currently only available for paid teams on Standard and Plus plans; Enterprise Grid support will be coming soon.

兩個都用 Slack 的團體可以開 Shared Channel,但之前只支援 Public Channel (參考「兩個都用 Slack 的公司可以直接在 Slack 上合作了」),現在則是支援 Private Channel 了。

可以兩個團體都是 Private:

也可以是單邊 Private,對另外一邊完全開放:

這個功能主要是用在 secret project 但又需要跟外部溝通的情況...

Amazon 西雅圖辦公室拿隔壁棟 Data Center 的廢熱當空調

Amazon 的其中一個辦公室拿隔壁 data center 的廢熱借來當自己辦公室的空調:「Amazon to use data centre waste heat to warm corporate offices」,原始報導在「The super-efficient heat source hidden below Amazon's Seattle headquarters」。除了嘗試省電省成本以外,對企業形象也比較好...

隔壁 Westin Building Exchange 的地址是「2001 6th Ave #300, Seattle, WA 98121」,辦公室則是在「2040 6th Ave, Seattle, WA 98121」,無論是從地址上看,或是 Google Maps 上可以看,都可以看出來兩棟就在旁邊而已,拉管線就簡單很多了。

預定二十五年省 80M 度電,所以一年大約是 3.2M 度,以「Seattle, WA Electricity Rates | Electricity Local」這邊給的數字來算,商業用店每度是 USD$0.068,每年大約省下 USD$217,600 (所以每年大約可以省下台幣六百萬),以 3800 人的辦公室來說其實有點微妙,不過以 PR 的角度還看其實就很划算了 XDDD:

It is expected, over the course of 25 years, to save approximately 80 million kWh of electricity use by Amazon.

不知道這套系統花多少錢...

AWS 提供 Hybrid Cloud 環境下 DNS 管理的說明

不知道為什麼出現在 browser tab 上,不知道是哪邊看到的... AWS 放出了一份文件,在講 hybrid cloud 環境下當你同時有一般 IDC 機房,而且使用內部 domain 在管理時,網路與 AWS 打通後要怎麼解決 DNS resolver 的問題:「Hybrid Cloud DNS Solutions for Amazon VPC」。

有些東西在官方的說明文件內都寫過,但是是 AWS 的特殊設計,這邊就會重複說明 XDDD

像是這份文件裡提到 Amazon DNS Server 一定會在 VPC 的 base 位置加二 (舉例來說,10.0.0.0/16 的 VPC,Amazon DNS Server 會在 10.0.0.2):

Amazon DNS Server
The Amazon DNS Server in a VPC provides full public DNS resolution, with additional resolution for internal records for the VPC and customer-defined Route 53 private DNS records.4 The AmazonProvidedDNS maps to a DNS server running on a reserved IP address at the base of the VPC network range, plus two. For example, the DNS Server on a 10.0.0.0/16 network is located at 10.0.0.2. For VPCs with multiple CIDR blocks, the DNS server IP address is located in the primary CIDR block.

在官方文件裡,則是在「DHCP Options Sets」這邊提到一樣的事情:

When you create a VPC, we automatically create a set of DHCP options and associate them with the VPC. This set includes two options: domain-name-servers=AmazonProvidedDNS, and domain-name=domain-name-for-your-region. AmazonProvidedDNS is an Amazon DNS server, and this option enables DNS for instances that need to communicate over the VPC's Internet gateway. The string AmazonProvidedDNS maps to a DNS server running on a reserved IP address at the base of the VPC IPv4 network range, plus two. For example, the DNS Server on a 10.0.0.0/16 network is located at 10.0.0.2. For VPCs with multiple IPv4 CIDR blocks, the DNS server IP address is located in the primary CIDR block.

另外也還是有些東西在官方的說明文件內沒看過,像是講到 Elastic Network Interface (ENI) 對 Amazon DNS Server 是有封包數量限制的;這點我沒在官方文件上找到,明顯在量太大的時候會中獎,然後開 Support Ticket 才會發現的啊 XDDD:

Each network interface in an Amazon VPC has a hard limit of 1024 packets that it can send to the Amazon Provided DNS server every second.

Anyway... 這份文件裡面提供三種解法:

  • Secondary DNS in a VPC,直接用程式抄一份到 Amazon Route 53 上,這樣 Amazon DNS Server 就可以直接看到了,這也是 AWS 在一般情況下比較推薦的作法。
  • Highly Distributed Forwarders,每台 instance 都跑 Unbound,然後針對不同的 domain 導開,這樣可以有效避開單一 ENI 對 Amazon DNS Server 的封包數量限制,但缺點是這樣的設計通常會需要像是 Puppet 或是 Chef 之類的軟體管理工具才會比較好設定。
  • Zonal Forwarders Using Supersede,就是在上面架設一組 Unbound 伺服器集中管理,透過 DHCP 設定讓 instance 用。但就要注意量不能太大,不然 ENI 對 Amazon DNS Server 的限制可能會爆掉 XD

都可以考慮看看...

新的 DNS Resolver:9.9.9.9

看到新的 DNS Resolver 服務,也拿到了還不錯的 IP address,9.9.9.9:「New “Quad9” DNS service blocks malicious domains for everyone」,服務網站是「Quad 9 | Internet Security and Privacy in a Few Easy Steps」,主打宣稱過濾已知的危險站台...

由政府單位、IBM 以及 Packet Clearing House 成立的:

The Global Cyber Alliance (GCA)—an organization founded by law enforcement and research organizations to help reduce cyber-crime—has partnered with IBM and Packet Clearing House to launch a free public Domain Name Service system.

也就是說,後面三家都不是專門做網路服務的廠商... 於是就會發現連 Client Subnet in DNS Queries (RFC 7871) 都沒提供,於是查出來的地區都不對,這對使用 DNS resolver 位置分配 CDN 節點的服務很傷啊... (或是其他類似服務)

這是 GooglePublic DNS (8.8.8.8) 查出來的:

;; ANSWER SECTION:
i.kfs.io.               576     IN      CNAME   kwc.kkcube.com.country.mp.kkcube.com.
kwc.kkcube.com.country.mp.kkcube.com. 21599 IN CNAME TW.kwc.kkcube.com.
TW.kwc.kkcube.com.      188     IN      CNAME   i.kfs.io.cdn.cloudflare.net.
i.kfs.io.cdn.cloudflare.net. 299 IN     A       104.16.244.238
i.kfs.io.cdn.cloudflare.net. 299 IN     A       104.16.245.238

;; Query time: 28 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sat Nov 18 05:30:23 CST 2017
;; MSG SIZE  rcvd: 181

這是 Quad9 (9.9.9.9) 查出來的:

;; ANSWER SECTION:
i.kfs.io.               1800    IN      CNAME   kwc.kkcube.com.country.mp.kkcube.com.
kwc.kkcube.com.country.mp.kkcube.com. 42702 IN CNAME US.kwc.kkcube.com.
US.kwc.kkcube.com.      300     IN      CNAME   i.kfs.io.cdn.cloudflare.net.
i.kfs.io.cdn.cloudflare.net. 300 IN     A       104.16.245.238
i.kfs.io.cdn.cloudflare.net. 300 IN     A       104.16.244.238

;; Query time: 294 msec
;; SERVER: 9.9.9.9#53(9.9.9.9)
;; WHEN: Sat Nov 18 05:30:27 CST 2017
;; MSG SIZE  rcvd: 181

再來一點是,在科技領域相信政府單位通常都是一件錯誤的事情,我 pass... XD

下一代的 Tor Hidden Service

Tor 公佈了下一代的 Hidden Service (Onion Service):「Tor's Fall Harvest: the Next Generation of Onion Services」。

三年前 Facebook 自己暴力算出 facebookcorewwwi.onion 這個很特別的名字 (參考「Facebook 證明 Tor 的 Hidden Service 不安全」),這陣子連紐約時報也能暴力算出 nytimes3xbfgragh.onion 這個好名字 (參考「紐約時報網站上 Tor 的 Hidden Service (i.e. Tor Onion Service)」,這讓只有 16 chars 的 hostname 的 hashed-space 不夠大的問題愈來愈明顯 (只有 80 bits 的空間)。

如果你也想要找出一個有趣的 hostname 的話,可以用 lachesis/scallion 這樣的工具,這程式用 CPU 產生出 RSA key 後,再用 GPU 算 SHA-1

The inital RSA key generation is done the CPU. An ivybridge i7 can generate 51 keys per second using a single core. Each key can provide 1 gigahash worth of exponents to mine and a decent CPU can keep up with several GPUs as it is currently implemented.

也因為如此,Facebook 與紐約時報在上線時並不是直接在 Hidden Service 上裸奔,而是上了 HTTPS 作為 workaround,以避免資料外洩。

但這畢竟是 workaround,Tor 的人還是希望協定本身就可以提供一個夠安全的架構,而花了四年多發展出下一代的 Hidden Service,也就是這次提到的成果了。

最大的改變就是 hostname 變長很多了,從本來的 16 chars 變成 56 chars:

And finally from the casuals user's PoV, the only thing that changes is that new onions are bigger, tastier and they now look like this: 7fa6xlti5joarlmkuhjaifa47ukgcwz6tfndgax45ocyn4rixm632jid.onion.

hostname 變長主要是因為把整個 256 bits public key 放進去,可以從 spec 看到:

6. Encoding onion addresses [ONIONADDRESS]

   The onion address of a hidden service includes its identity public key, a
   version field and a basic checksum. All this information is then base32
   encoded as shown below:

     onion_address = base32(PUBKEY | CHECKSUM | VERSION) + ".onion"
     CHECKSUM = H(".onion checksum" | PUBKEY | VERSION)[:2]

     where:
       - PUBKEY is the 32 bytes ed25519 master pubkey of the hidden service.
       - VERSION is an one byte version field (default value '\x03')
       - ".onion checksum" is a constant string
       - CHECKSUM is truncated to two bytes before inserting it in onion_address

  Here are a few example addresses:

       pg6mmjiyjmcrsslvykfwnntlaru7p5svn6y2ymmju6nubxndf4pscryd.onion
       sp3k262uwy4r2k3ycr5awluarykdpag6a7y33jxop4cs2lu5uz5sseqd.onion
       xa4r2iadxm55fbnqgwwi5mymqdcofiu3w6rpbtqn7b2dyn7mgwj64jyd.onion

   For more information about this encoding, please see our discussion thread
   at [ONIONADDRESS-REFS].

這是因為在 ECC 的安全性被廣泛認可後,ECC 的優點就被拿出來用在這次設計上了:

  • 256 bits 的 ECC key 強度大約是 3072 bits RSA key (以現在最好的攻擊演算法來估算)。
  • 直接放 public key 不需要經過 hash function 計算,可以避免掉 hash function 被找到 collision 時的風險。

於是因為 hostname 放的下,就硬塞進去了 XDDD

不過如果要玩的人需要裝 alpha 版本,目前的 stable 版本還沒有這個功能:

Tor as of version 0.3.2.1-alpha supports the next-gen onion services protocol for clients and services! As part of this release, ​the core of proposal 224 has been implemented and is available for experimentation and testing by our users.

Let's Encrypt 的 Embed SCT 支援

翻到 Let's EncryptUpcoming Features 時看到:

Embed SCT receipts in certificates
ETA: February, 2018

對 Embed SCT 不熟,所以查了查這個功能。

這指的是在簽發 SSL certficiate 後,把資料丟給 Certificate Transparency (CT) 伺服器後,伺服器會提供 signed certificate timestamp (SCT);而這個資料放到 SSL certificate 內叫做 Embed SCT:(出自 CT 的 FAQ)

What is an SCT?
An SCT is a signed certificate timestamp. When a certificate authority or a server operator submits a certificate to a log, the log responds with an SCT. An SCT is essentially a promise that the log server will add the certificate to the log in a specific time. The time, known as the maximum merge delay (MMD), helps ensure that certificates are added to logs in a reasonable time. The SCT accompanies the certificate until the certificate is revoked. A TLS server must present the SCT to a TLS client (along with the SSL certificate) during the TLS handshake.

當使用 ECC 時會小於 100 bytes:

How big is an SCT?
SCTs are less than 100 bytes, assuming elliptic curve signatures are used.

這樣才能試著解釋前幾天提到要拔掉 HPKP 的事情:「Chromium 內提案移除 HPKP (HTTP Public Key Pinning)」,也就是為什麼他們是提 CT 解,而不是 DNS CAA 解...

不過我記得 CT server 可以自己架自己 submit 不是嗎?後來有另外規定一定要用第三方的嗎?這樣又很怪...

Archives