Update the SOCKS proxy to use the new RelayManager

[zeroSteiner]

This updates the SOCKS5 proxy module to use the newish RelayManager added in #20677 . The result is a net reduction in code and some performance improvements.

Requires rapid7/rex-core#45

Verification

List the steps needed to make sure this thing works

• Start msfconsole
• use auxiliary/server/socks_proxy
• Use the proxy, make sure it's working correctly

Simple Benchmarking

This simple benchmark at least showed that when making repeated GET requests to a local server that is listening, the operation finished in about half the time.

smcintyre@fedora:~/Repositories/metasploit-framework$  for i in $(seq 1 100); do
    curl --socks5 127.0.0.1:1080 http://127.0.0.1:8000/ -o /dev/null -s -w "%{time_connect} %{time_total}\n"
  done | awk '{sum+=$2; n++} END {print "avg:", sum/n}'
avg: 0.0104874
smcintyre@fedora:~/Repositories/metasploit-framework$  for i in $(seq 1 100); do
    curl --socks5 127.0.0.1:1080 http://127.0.0.1:8000/ -o /dev/null -s -w "%{time_connect} %{time_total}\n"
  done | awk '{sum+=$2; n++} END {print "avg:", sum/n}'
avg: 0.014277
smcintyre@fedora:~/Repositories/metasploit-framework$  for i in $(seq 1 100); do
    curl --socks5 127.0.0.1:1080 http://127.0.0.1:8000/ -o /dev/null -s -w "%{time_connect} %{time_total}\n"
  done | awk '{sum+=$2; n++} END {print "avg:", sum/n}'
avg: 0.0125423

smcintyre@fedora:~/Repositories/metasploit-framework$ # new code tests start here

smcintyre@fedora:~/Repositories/metasploit-framework$  for i in $(seq 1 100); do
    curl --socks5 127.0.0.1:1080 http://127.0.0.1:8000/ -o /dev/null -s -w "%{time_connect} %{time_total}\n"
  done | awk '{sum+=$2; n++} END {print "avg:", sum/n}'
avg: 0.00496531
smcintyre@fedora:~/Repositories/metasploit-framework$ 
smcintyre@fedora:~/Repositories/metasploit-framework$  for i in $(seq 1 100); do
    curl --socks5 127.0.0.1:1080 http://127.0.0.1:8000/ -o /dev/null -s -w "%{time_connect} %{time_total}\n"
  done | awk '{sum+=$2; n++} END {print "avg:", sum/n}'
avg: 0.00502326
smcintyre@fedora:~/Repositories/metasploit-framework$  for i in $(seq 1 100); do
    curl --socks5 127.0.0.1:1080 http://127.0.0.1:8000/ -o /dev/null -s -w "%{time_connect} %{time_total}\n"
  done | awk '{sum+=$2; n++} END {print "avg:", sum/n}'
avg: 0.00545381
smcintyre@fedora:~/Repositories/metasploit-framework$ 

[Copilot]

Pull request overview

This PR refactors the SOCKS5 proxy implementation to use Rex::IO::RelayManager for TCP relaying instead of the local per-socket relay mixin, and updates the rex-core dependency to a git-based version that provides the needed relay manager behavior.

Changes:

• Replace the custom SOCKS5 TcpRelay implementation with Rex::IO::RelayManager-based relays.
• Add a relay_manager to the SOCKS5 server and use it from ServerClient.
• Switch rex-core dependency to a specific git branch/revision in Bundler.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

File	Description
lib/rex/proto/proxy/socks5/server.rb	Initializes and exposes a RelayManager instance for use by SOCKS5 clients.
lib/rex/proto/proxy/socks5/server_client.rb	Removes bespoke relay threading and wires sockets through the shared RelayManager; updates error logging and stop behavior.
Gemfile	Pins rex-core to a git branch to pick up RelayManager changes.
Gemfile.lock	Locks Bundler to the git-sourced rex-core revision.

---

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[cgranleese-r7]

Maybe if we have the cycles add some tests for this would be nice!

[dledda-r7]

msf payload(windows/meterpreter_reverse_tcp) > use auxiliary/server/socks_proxy
msf auxiliary(server/socks_proxy) > info

       Name: SOCKS Proxy Server
     Module: auxiliary/server/socks_proxy
    License: Metasploit Framework License (BSD)
       Rank: Normal

Provided by:
  sf <stephen_fewer@harmonysecurity.com>
  Spencer McIntyre
  surefire

Available actions:
    Name   Description
    ----   -----------
=>  Proxy  Run a SOCKS proxy server

Check supported:
  No

Basic options:
  Name     Current Setting  Required  Description
  ----     ---------------  --------  -----------
  SRVHOST  0.0.0.0          yes       The local host or network interface to listen on. This must be an address on the local machine or 0.0.0.0 to listen
                                      on all addresses.
  SRVPORT  1080             yes       The port to listen on
  SRVSSL   false            no        Negotiate SSL/TLS for local server connections
  VERSION  5                yes       The SOCKS version to use (Accepted: 4a, 5)


  When VERSION is 5:

  Name      Current Setting  Required  Description
  ----      ---------------  --------  -----------
  PASSWORD                   no        Proxy password for SOCKS5 listener
  USERNAME                   no        Proxy username for SOCKS5 listener

Description:
  This module provides a SOCKS proxy server that uses the builtin Metasploit routing to relay connections.


View the full module info with the info -d command.

msf auxiliary(server/socks_proxy) > run
[*] Auxiliary module running as background job 0.
msf auxiliary(server/socks_proxy) > 
[*] Starting the SOCKS proxy server

msf auxiliary(server/socks_proxy) > jobs

Jobs
====

  Id  Name                           Payload  Payload opts
  --  ----                           -------  ------------
  0   Auxiliary: server/socks_proxy

msf auxiliary(server/socks_proxy) > 


┌──(kali㉿kali)-[~/Documents/github/metasploit-framework]
└─$ curl --proxy socks5://127.0.0.1:1080 https://www.google.com | wc -c
  % Total    % Received % Xferd  Average Speed  Time    Time    Time   Current
                                 Dload  Upload  Total   Spent   Left   Speed
100  79421   0  79421   0      0 195.4k      0                              0
79421
                                                                                                                                                            
┌──(kali㉿kali)-[~/Documents/github/metasploit-framework]
└─$  

[smcintyre-r7]

Release Notes

This updates the SOCKS proxy module to use the new fiber-based relay manager internally. The result is a reduction in code and improved performance.