A command-line tool to interact with TCP sockets opened by other processes on the same Linux machine.
Allows you to search, select, and duplicate existing sockets (via pidfd_getfd), send data or files through them, and receive data with a configurable timeout.

• List TCP sockets opened by processes, optionally filtered by PID or process name.
• Display remote IP address and port for each socket.
• Select a socket from search results to interact with.
• Send arbitrary strings or entire files into the selected socket.
• Receive data from the socket with a timeout and optionally save to a file.
• Configure receive timeout.
• Simple interactive shell interface with helpful commands.

• Linux kernel 5.6 or newer (for pidfd_open and pidfd_getfd syscalls 78B1 )
• Root privileges to access other processes' file descriptors
• GCC to compile

gcc -o socket_injector socket_injector.c

Run the program as root :

Interactive CLI :

sudo ./socket_injector

Non-interactive mode :

sudo ./socket_injector --pid 3458 -f 4 --send Hello_World

• help Show help with available commands.

• search [pattern] List all sockets. If a pattern is given, filter by PID or process name containing the pattern.

• select <index> Select a socket from the last search results by its index.

• send <string> Send a string to the selected socket.

• sendf <file> Send the contents of a file to the selected socket.

• rec [file] Receive data from the socket with a timeout (default 5 seconds). If file is provided, save received data to it, otherwise print to stdout. Displays the number of bytes received after completion.

• timeout <seconds> Set the receive timeout duration (in seconds).

• quit Exit the program.

Help :

# ./js5 --help
Usage:
  program [options]
Options:
  -p, --pid PID           Specify PID
  -s, --socket FD         Specify socket fd
  -S, --send STRING       Send string to socket
  -F, --sendf FILE        Send file content to socket
  -r, --rec [FILE]        Receive from socket, output to stdout or FILE if specified
  search [pattern]        Search sockets optionally filtering by pattern
  -h, --help              Show this help

If no arguments are provided, starts interactive shell.

Run :

> search ssh
Found 2 socket(s):
[0] PID=1234 (sshd) FD=5 -> 192.168.1.10:22
[1] PID=5678 (ssh) FD=4 -> 192.168.1.11:22

> select 0
Selected entry [0]

> send Hello World
Data sent: 11 bytes

> rec
Received 34 bytes

> quit
Bye.

• This tool requires root access to open file descriptors from other processes.
• The program duplicates the file descriptor using Linux pidfd_getfd syscall to reuse the same socket.
• Receiving data uses select() with a configurable timeout to wait for incoming data.
• Tested on Linux kernel 5.6+.