urserversfine

Windows subsystem for Android
Install dnsutils termux-api python
IPv6 doesn’t work
https://source.chromium.org/chromium/chromium/src/+/main:net/base/net_error_list.h
Chromium Code
CONNECTION_RESET → TCP Reset → ConnectionResetError
CONNECTION_CLOSED → TCP FIN → ??
CONNECTION_REFUSED → Generic → ConnectionRefusedError
CONNECTION_ABORTED → TCP FIN without ACK → ConnectionAbortedError

Oracle Cloud testing
UFW open port, but no services running/listening, SYN → RST → REFUSED
UFW port closed, service is running SYN → retransmission → Timeout

• packet silently dropped by DENY, which is to DROP
• when set to REJECT, it doesn’t drop the packet, same symptom as open port but no service

General

• MAC address of WiFi, use API to lookup vendor
• lookup public IP address, city, ISP, ASN
• os.get_terminal_size() for formatting

DNS Resolver
Verify if the UDP 53 resolver or DoH is reachable

Real DNS lookup resolver
https://nslookup.techweirdo.net/api/lookup?domain=doubleclick.net

• uses URL parameter domain= for lookup
• NXDOMAIN returns nothing
  https://networkcalc.com/api/dns/lookup/yycdn.vttc.dpdns.org
• uses api/dns/lookup
• NXDOMAIN returns status:
  https://d53.co/cloudflare/a/langleyhome.mywire.org
• uses /a/site
• require HTML parsing
  https://dnsviahttp.com/
• url parameter
• require HTML parsing

payload = 'qname=langleyhome.mywire.org&qtype=A'

Cloudflare DoH

curl -H 'accept: application/dns-json' 'https://cloudflare-dns.com/dns-query?name=example.com&type=A'

Other resolvers

• UDP 53 plaintext (nslookup)
• DNS Over HTTPS (using cURL or dig)

DNS
Grab configured DNS from dumpsys, if cannot get then uses default which is 8.8.8.8
Using nslookup
Using curl DNS lookup
Check against real API DNS providers and see if it poisoned

• or NXDOMAIN
• if its ::1, 0.0.0.0 or 127.0.0.1 will return poisoned by default
• using ipaddress, if is_loopback and not is_global