透過Proxyを設定したら証明書なしに何故か動いちゃった話

こちらの投稿
Squid proxy - a short guide (forward & transparent proxy examples, SSL bumping, links to guides) -Reddit
などを参考にSquidで透過Proxyの設定をしたら，自己署名ルート証明書を追加せずに動いちゃった話です。

環境

PC: ThinkPad T490 Arch Linux
認証付きProxy必須の環境
Azure上に構築したHTTP ProxyをSSHポートフォワーディングで持ってきている
create_apでWi-Fiを飛ばしていて，スマホはDronyを使いHTTP Proxy非対応のアプリもProxy経由で通信できるようにしている

Squidで複数のProxyを操る -Qiita より

設定ファイルとか

proxy.server.jp:8080(仮)と0.0.0.0:8888を親に持つSquidの設定ファイル：

/etc/squid/squid.conf

#
# Recommended minimum configuration:
#

# Example rule allowing access from your local networks.
# Adapt to list your (internal) IP networks from where browsing
# should be allowed
acl localnet src 0.0.0.1-0.255.255.255  # RFC 1122 "this" network (LAN)
acl localnet src 10.0.0.0/8             # RFC 1918 local private network (LAN)
acl localnet src 100.64.0.0/10          # RFC 6598 shared address space (CGN)
acl localnet src 169.254.0.0/16         # RFC 3927 link-local (directly plugged) machines
acl localnet src 172.16.0.0/12          # RFC 1918 local private network (LAN)
acl localnet src 192.168.0.0/16         # RFC 1918 local private network (LAN)
acl localnet src fc00::/7               # RFC 4193 local private network range
acl localnet src fe80::/10              # RFC 4291 link-local (directly plugged) machines

acl SSL_ports port 443
acl Safe_ports port 80          # http
acl Safe_ports port 21          # ftp
acl Safe_ports port 443         # https
acl Safe_ports port 70          # gopher
acl Safe_ports port 210         # wais
acl Safe_ports port 1025-65535  # unregistered ports
acl Safe_ports port 280         # http-mgmt
acl Safe_ports port 488         # gss-http
acl Safe_ports port 591         # filemaker
acl Safe_ports port 777         # multiling http
acl CONNECT method CONNECT

#
# Recommended minimum Access Permission configuration:
#
# Deny requests to certain unsafe ports
http_access deny !Safe_ports

# Deny CONNECT to other than secure SSL ports
http_access deny CONNECT !SSL_ports

# Only allow cachemgr access from localhost
http_access allow localhost manager
http_access deny manager

on_unsupported_protocol tunnel all
# We strongly recommend the following be uncommented to protect innocent
# web applications running on the proxy server who think the only
# one who can access services on "localhost" is a local user
#http_access deny to_localhost

#
# INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
#

cache_peer proxy.server.jp parent 8080 0 no-query no-netdb-exchange no-digest login=USER:PASS
proxy-only
cache_peer 0.0.0.0    parent 8888 0 no-query no-netdb-exchange no-digest default

acl sorting time SMTWHF 1:00-6:00
acl blacklist dstdomain "/usr/local/etc/squid/blacklist"
acl blog url_regex blog
acl blacklist_day dstdomain "/usr/local/etc/squid/blacklist_day"

acl status http_status !200

http_port 7080 intercept
https_port 7443 intercept ssl-bump \
 generate-host-certificates=on \
 dynamic_cert_mem_cache_size=4MB \
 cert=/etc/squid/cert/myCA.pem \
 key=/etc/squid/cert/myCA.pem

acl step1 at_step SslBump1
acl step2 at_step SslBump2
acl step3 at_step SslBump3

#ssl_bump peek step1    # <- enabling this breaks it
ssl_bump stare step2
ssl_bump bump step3
# Uncommenting this may also break bumping.
#ssl_bump bump all
# Example rule allowing access from your local networks.
# Adapt localnet in the ACL section to list your (internal) IP networks
# from where browsing should be allowed
http_access allow localnet
http_access allow localhost
http_access allow all


# And finally deny all other access to this proxy
http_access deny all

# Squid normally listens to port 3128
http_port 3354
icp_port 0

# Uncomment and adjust the following to add a disk cache directory.
#cache_dir ufs /var/cache/squid 100 16 256

# Leave coredumps in the first cache dir
coredump_dir /var/cache/squid

#
# Add any of your own refresh_pattern entries above these.
#
refresh_pattern ^ftp:           1440    20%     10080
refresh_pattern ^gopher:        1440    0%      1440
refresh_pattern -i (/cgi-bin/|\?) 0     0%      0
refresh_pattern .               0       20%     4320

# サブProxyがあれば設定

# ローカルネットワークセグメントには親プロキシを通さずダイレクトアクセス
acl developersegments1 dst 192.168.0.0/24
always_direct allow developersegments1

never_direct allow all

# キャッシュしない
cache deny all

#cache_peer_access proxy.server.jp deny sorting
cache_peer_access proxy.server.jp deny blacklist sorting
cache_peer_access proxy.server.jp deny blog sorting
cache_peer_access proxy.server.jp deny blacklist_day
cache_peer_access proxy.server.jp deny status

iptablesで追加した設定
ap0に端末(スマートフォン)が接続されている

iptables -t nat -A PREROUTING -i ap0 -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 7080
iptables -t nat -A PREROUTING -i ap0 -p tcp -m tcp --dport 443 -j REDIRECT --to-ports 7443

理由

†原因究明中†