Bug in upstream proxy feature

[mjkim610]

Proxify version:

v0.0.16

Current Behavior:

-hp flag does not seem to work. Traffic is not forwarded to upstream proxy.

"main" proxify instance:

❯ go build ; ./proxify -http-proxy http://127.0.0.1:9999 -vv

                       _ ___    
   ___  _______ __ __ (_) _/_ __
  / _ \/ __/ _ \\ \ // / _/ // /
 / .__/_/  \___/_\_\/_/_/ \_, / 
/_/                      /___/

                projectdiscovery.io

[INF] Current proxify version v0.0.16 (latest)
[INF] HTTP Proxy Listening on 127.0.0.1:8888
[INF] Socks5 Proxy Listening on 127.0.0.1:10080
[INF] Saving proxify logs to proxify_logs.jsonl
[INF] Saving proxify logs (raw) to proxify_logs
[INF] Using upstream HTTP proxies: ["http://127.0.0.1:9999"]
GET http://www.facebook.com/ HTTP/1.1
Accept: */*
Accept-Encoding: 
Connection: close
User-Agent: curl/8.7.1

GET http://www.facebook.com/ HTTP/1.1
Accept: */*
Accept-Encoding: 
Connection: close
User-Agent: curl/8.7.1

HTTP/1.1 301 Moved Permanently
Connection: close
Content-Type: text/plain
Date: Wed, 10 Sep 2025 06:47:33 GMT
Location: https://www.facebook.com/
Server: proxygen-bolt
Content-Length: 0

"upstream" proxify instance (receives no traffic):

❯ ./proxify -ha 127.0.0.1:9999 -sa 127.0.0.1:10090 -vv -sr proxify_logs_upstream -o proxify_logs_upstream.jsonl

                       _ ___    
   ___  _______ __ __ (_) _/_ __
  / _ \/ __/ _ \\ \ // / _/ // /
 / .__/_/  \___/_\_\/_/_/ \_, / 
/_/                      /___/

                projectdiscovery.io

[INF] Current proxify version v0.0.16 (latest)
[INF] HTTP Proxy Listening on 127.0.0.1:9999
[INF] Socks5 Proxy Listening on 127.0.0.1:10090
[INF] Saving proxify logs to proxify_logs_upstream.jsonl
[INF] Saving proxify logs (raw) to proxify_logs_upstream
- Ctrl+C pressed in Terminal

Expected Behavior:

"upstream" proxy receives traffic. I can confirm it is working in v0.0.8.

"main" proxify instance:

❯ go build ; ./proxify -http-proxy http://127.0.0.1:9999 -vv

                       _ ___    
   ___  _______ __ __ (_) _/_ __
  / _ \/ __/ _ \\ \ // / _/ // /
 / .__/_/  \___/_\_\/_/_/ \_, / 
/_/                      /___/  v0.0.8

                projectdiscovery.io

[INF] HTTP Proxy Listening on 127.0.0.1:8888
[INF] Socks5 Proxy Listening on 127.0.0.1:10080
[INF] Saving proxify traffic to logs
[INF] Using upstream HTTP proxies: ["http://127.0.0.1:9999"]
2025/09/10 15:49:32 [001] INFO: Got request / www.facebook.com GET http://www.facebook.com/
GET http://www.facebook.com/ HTTP/1.1
Accept: */*
Proxy-Connection: Keep-Alive
User-Agent: curl/8.7.1

2025/09/10 15:49:32 [001] INFO: Sending request GET http://www.facebook.com/
2025/09/10 15:49:32 [001] INFO: Received response 301 Moved Permanently
HTTP/1.1 301 Moved Permanently
Connection: keep-alive
Content-Type: text/plain
Date: Wed, 10 Sep 2025 06:49:32 GMT
Location: https://www.facebook.com/
Server: proxygen-bolt
Content-Length: 0

2025/09/10 15:49:32 [001] INFO: Copying response to client 301 Moved Permanently [301]
2025/09/10 15:49:32 [001] INFO: Copied 0 bytes to client error=<nil>

"upstream" proxify instance:

❯ ./proxify -ha 127.0.0.1:9999 -sa 127.0.0.1:10090 -vv 

                       _ ___    
   ___  _______ __ __ (_) _/_ __
  / _ \/ __/ _ \\ \ // / _/ // /
 / .__/_/  \___/_\_\/_/_/ \_, / 
/_/                      /___/  v0.0.8

                projectdiscovery.io

[INF] HTTP Proxy Listening on 127.0.0.1:9999
[INF] Socks5 Proxy Listening on 127.0.0.1:10090
[INF] Saving proxify traffic to logs
2025/09/10 15:49:32 [001] INFO: Got request / www.facebook.com GET http://www.facebook.com/
GET http://www.facebook.com/ HTTP/1.1
Accept: */*
Accept-Encoding: gzip
User-Agent: curl/8.7.1

2025/09/10 15:49:32 [001] INFO: Sending request GET http://www.facebook.com/
2025/09/10 15:49:32 [001] INFO: Received response 301 Moved Permanently
HTTP/1.1 301 Moved Permanently
Connection: keep-alive
Content-Type: text/plain
Date: Wed, 10 Sep 2025 06:49:32 GMT
Location: https://www.facebook.com/
Server: proxygen-bolt
Content-Length: 0

2025/09/10 15:49:32 [001] INFO: Copying response to client 301 Moved Permanently [301]
2025/09/10 15:49:32 [001] INFO: Copied 0 bytes to client error=<nil>

Steps To Reproduce:

1. Run ./proxify -http-proxy http://127.0.0.1:9999 -vv
2. Run some upstream proxy (another proxify instance, burp suite proxy, etc.)
3. Send some traffic
4. Verify that the upstream proxy is not receiving traffic

Anything else:

[mjkim610]

Related: #713
Given green light by pdteam on discord, I will work on this.

[mjkim610]

While working on this, I discovered several issues. I am currently working on them one by one.

• Update documentation and code to follow coding convention #733
• Fail fast when both HTTP and SOCKS5 proxies are set #734
• Fix upstream proxy bug #735

[dogancanbakir]

I was unable to reproduce the issue; I was able to successfully receive data in the upstream proxy, in this case, Burp Suite.

[mjkim610]

I was unable to reproduce the issue; I was able to successfully receive data in the upstream proxy, in this case, Burp Suite.

Hi @dogancanbakir. Can you provide the steps you took?

Here are my steps:

Setup

Burp suite config:

Session 1:

❯ cd [...]/proxify/cmd/proxify
❯ git checkout v0.0.16
❯ go build ; ./proxify -hp http://127.0.0.1:8080/

Session 2:

curl -x http://127.0.0.1:8888/ www.google.com

Before fix

No packet intercepted

After fix

[mjkim610]

Hi @dogancanbakir , any update?

[mjkim610]

All related PRs merged, closing issue.
Please re-open if there are issues.