Thread failed to connect

[raff-s]

Thanks for this amazing tool, I was able to run it on my old machine but on this one I'm seeing the following error

java.net.ConnectException: Connection refused
	at java.base/sun.nio.ch.Net.connect0(Native Method)
	at java.base/sun.nio.ch.Net.connect(Net.java:579)
	at java.base/sun.nio.ch.Net.connect(Net.java:568)
	at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:588)
	at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:327)
	at java.base/java.net.Socket.connect(Socket.java:633)
	at java.base/sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:304)
	at java.base/sun.security.ssl.SSLSocketImpl.<init>(SSLSocketImpl.java:184)
	at java.base/sun.security.ssl.SSLSocketFactoryImpl.createSocket(SSLSocketFactoryImpl.java:137)
	at burp.ThreadedRequestEngine.sendRequests(ThreadedRequestEngine.kt:141)
	at burp.ThreadedRequestEngine.access$sendRequests(ThreadedRequestEngine.kt:17)
	at burp.ThreadedRequestEngine$1.invoke(ThreadedRequestEngine.kt:50)
	at burp.ThreadedRequestEngine$1.invoke(ThreadedRequestEngine.kt:49)
	at kotlin.concurrent.ThreadsKt$thread$thread$1.run(Thread.kt:30)

This happens on portswigger labs or even google.com or example.com
I tried the debug.py script when I change concurrentConnections from 1 to 5 it starts failing after a couple of requests.
Changing Engine.THREADED to Engine.BURP fixes the problem.
Using the regular intruder with a pool of 30 also works fine, so I think it's something specific to TurboIntruder.
Any help would be great, thanks

Config
MacBook Air (M1, 2020)

➜  ~ java -version
openjdk version "17.0.4" 2022-07-19
OpenJDK Runtime Environment Homebrew (build 17.0.4+0)
OpenJDK 64-Bit Server VM Homebrew (build 17.0.4+0, mixed mode, sharing)

➜  ~ sw_vers
ProductName:	macOS
ProductVersion:	12.3
BuildVersion:	21E230

[albinowax]

That's really strange, I'm not sure what would cause that, looks like something unusual about your environment. Is your traffic going through any proxies or fancy firewalls that might be doing traffic shaping or suchlike?

Also, assuming you're currently running Burp via the jar, can you try using the installer version? This will put you on the same JRE as most users.

[raff-s]

I also thought that maybe was an issue with my VPN but turning it off didn't change anything
Originally I tried the installer version and then tried the JAR the outcome is the same.
Another thing I noticed is that the RPS is always 1 or 2 independently of the value of concurrentConnections

[albinowax]

That's a crazy low RPS. Are you seeing that regardless of the target domain? Maybe you've got an anti-virus that's doing some horrific local MITM stuff?

[raff-s]

Yes the RPS are always at 1 or 2.
I ran kill -9 -1 to kill all running processes and only open burp and it's the same.
I thought maybe was something to do with the wifi extender so I connected directly to the router and still no change
Running on an old windows PC it works great
I tried to run other tools that do concurrent connections like fuff and they work fine so maybe it's something to do with java in this OS, but I don't know enough about java to try to debug this

[albinowax]

I don't think that kill strategy would fix AV/endpoint-protection/malware issues, since they'll all be running as other users / root. I wouldn't be inclined to blame Java if you can see the issue on different JREs. It might be related to the flags I set on the socket but that feels unlikely.