If you’ve ever set up Universal Links for an iOS application, you know that the Apple App Site Association (AASA) file can sometimes be a headache. Just a single typo, a missing bracket, or a misconfigured HTTP header can break deep linking entirely.

To make this process a bit smoother, I recently built a simple, dependency-free Python tool that verifies AASA files right from the command line.

## What is an AASA File?

The Apple App Site Association (AASA) file is a JSON file that lives on your web server. It establishes a secure connection between your domain and your iOS app, proving to Apple that you own both. When a user clicks a Universal Link (like https://yourdomain.com/path), iOS checks this file to see if the link should open in your app instead of Safari.

For this to work, the AASA file must:
1. Be served over HTTPS with a valid certificate.
2. Be exposed exactly at /.well-known/apple-app-site-association or /apple-app-site-association.
3. Contain valid JSON syntax defining the applinks (and optionally webcredentials or appclips).

If everything is correct, Apple’s CDN will also eventually cache a copy at https://app-site-association.cdn-apple.com/a/v1/[yourdomain.com].

## The Problem: It’s Hard to See Why It Fails

Usually, when deep links stop working, you’re left guessing. Is the file missing? Did the server return the wrong caching headers? Did my JSON syntax break when I updated it?

There are some web-based validators out there, but I wanted something I could run quickly in terminal, integrate into CI/CD pipelines, or just use locally without relying on third-party sites.

## Building verify_aasa.py

I decided to build a simple Python script called verify_aasa.py. The goal was to check the common endpoints where an AASA file might live, fetch it, parse the JSON, and validate its structural integrity.

### 1. Fetching the File

The script checks three distinct locations:

python
paths = [
f"https://{domain}/.well-known/apple-app-site-association",
f"https://{domain}/apple-app-site-association",
f"https://app-site-association.cdn-apple.com/a/v1/{domain}"
]


It iterates through these paths using Python’s built-in urllib.request. If it succeeds in pulling down the valid file, it confirms the HTTP status and notes the Content-Type returned by the server.

*Note: One common hangup is that local Python environments on macOS sometimes struggle with root SSL certificates. To make the tool robust, I added a quick fallback behavior: if the certifi module is available, it uses that for validation; otherwise, it bypasses SSL validation and prints a warning so the user isn’t stuck behind a local configuration error.*

### 2. Validating the JSON

Once it has the file, the next step is parsing it. If the AASA file has trailing commas or weird quotes, json.loads() will throw an error immediately, simulating the confusion iOS might experience.

Assuming it passes the JSON decode, the script validates the structure:

python
if 'applinks' in data:
applinks = data['applinks']
if 'details' in applinks:
for i, app in enumerate(applinks['details']):
appID = app.get('appID')
appIDs = app.get('appIDs')
# Check for modern 'components' or legacy 'paths'
# ...


A common issue nowadays is transitioning from the legacy paths routing to the modern components routing, as well as the transition from appID (string) to appIDs (array). The script validates that at least one of these is correctly defined for each block.

It also supports checking for the existence of webcredentials (Shared Web Credentials) and appclips (App Clips configurations).

## Running the Tool

Running the tool is simple:

bash
python3 verify_aasa.py apple.com


Which produces an output like this:


Verifying AASA file for domain: apple.com

Summary: AASA file syntax looks good!


## Wrapping Up

Building this little tool was a great reminder of how useful small, purpose-built CLI utilities can be. No dependencies (unless you want certifi for strict SSL), no web interfaces, just a quick sanity check to ensure iOS will swallow your AASA file correctly.

You can grab the script and use it in your own projects whenever Universal Links start acting up!
https://gist.github.com/darcyliu/0f15d22751829f2fa4f5c811e15b67c8

-EOF-

一番研究之后发现是 MTU 值偏低导致，在不调整 MTU 的情况下，可以更改 KexAlgorithms 或者 MACs 试试。

ssh root@10.10.10.10 -v -o KexAlgorithms=ecdh-sha2-nistp521
ssh root@10.10.10.10 -v -o MACs=hmac-sha2-256


-EOF-

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方法二：
Using Terminal:

sips -g format -g pixelWidth -g pixelHeight -g hasAlpha path/to/image.jpg

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curl https://github.com/{username}.keys >> ~/.ssh/authorized_keys

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psql -U postgres -c "CREATE DATABASE $DB_NAME;"

创建新的用户

psql -U postgres -c "CREATE USER $DB_USER WITH PASSWORD '$DB_PASSWORD';"

将新数据库的所有权限授予新用户

psql -U postgres -c "GRANT ALL PRIVILEGES ON DATABASE $DB_NAME TO $DB_USER;"

删除数据库

psql -U postgres -c "DROP DATABASE IF EXISTS $DB_NAME;"

删除用户

psql -U postgres -c "DROP USER IF EXISTS $DB_USER;"

-EOF-

cat /etc/nginx/nginx.conf
user www-data;
worker_processes auto;
pid /run/nginx.pid;
error_log /var/log/nginx/error.log;
include /etc/nginx/modules-enabled/*.conf;

如上 nginx 所使用的 user 为 www-data.
2. 将 WordPress 的文件 Owner 更改成 web server user, 比如：

chown -R www-data:www-data /the/folder/place/the/wordpress/

重新刷新页面即可。
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sysctl net.inet.ip.forwarding
sysctl net.inet6.ip6.forwarding

我们可以通过设置该值为1开启IP包转发功能。

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sysctl net.inet6.ip6.forwarding=1

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Top Issues

Server error (5xx)
We recommend that you fix these issues when possible to enable the best experience and coverage in Google Search.
检查日志发现如下内容：

2023/12/12 01:23:45 [error] 2175086#0: *57111 connect() to unix:/run/php-fpm/www.sock failed (11: Resource temporarily unavailable) while connecting to upstream, client: 192.3.114.12, server: example.com, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/run/php-fpm/www.sock:", host: "example.com", referrer: "http://example.com/"

于是跑了一遍压力测试，发现将近一半的请求都遇到5xx错误，同时日志中产生如上记录。

wrk -t12 -c400 -d30s https://ioio.name


便因此做了一下研究，主要参考 11: Resource temporarily unavailable, while connecting to upstream + Bad Gateway (Nginx)

通过执行如下命令调整了 net.core.somaxconn 及 net.core.netdev_max_backlog

echo "net.core.somaxconn = 65535" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p
echo "net.core.netdev_max_backlog = 65535" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p


更新nginx配置文件，给 FastCGI service 添加

fastcgi_keep_conn on;

然后重启服务

systemctl restart php-fpm.service
systemctl restart nginx

再次运行压力测试，错误消失。

wrk -t12 -c400 -d30s https://ioio.name
Running 30s test @ https://ioio.name
12 threads and 400 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 180.51ms 88.60ms 1.91s 89.36%
Req/Sec 109.17 32.60 212.00 71.29%
39114 requests in 30.08s, 1.86GB read
Socket errors: connect 158, read 0, write 0, timeout 0
Requests/sec: 1300.31
Transfer/sec: 63.29MB

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pkg update
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2. Install PostgreSQL 13

pkg install postgresql13-server postgresql13-client

3. Add the PostgreSQL to the system boot:

sysrc postgresql_enable=yes

4. Initialize the PostgreSQL database

/usr/local/etc/rc.d/postgresql initdb

5. Start the PostgreSQL service and check its status

service postgresql start
service postgresql status

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1. Inspect the configuration for kubernetes-dashboard

kubectl -n kubernetes-dashboard describe deployments kubernetes-dashboard

You may see --auto-generate-certificates in the **arg** section.

2. Update the configuration to add --token-ttl=0 to disable the session timeout; add -enable-skip-login to enable the skip login button.

kubectl -n kubernetes-dashboard edit deployments kubernetes-dashboard


Args:
--auto-generate-certificates
--token-ttl=0
--enable-skip-login
--enable-insecure-login

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