22.3 Debugging FreeBSD with IDA Pro

IDA Pro supports remote debugging using a client-server architecture. The Windows side runs the IDA Pro client, while the FreeBSD side runs the linux_server debug server through the Linux compatibility layer. This section is based on IDA Pro 9.3.260213 Windows x64.

IDA Pro 9.3.260213 Windows x64

Remote Debugging Principle

IDA Pro's remote debugging uses a client-server architecture: a debug server program runs on the target system (FreeBSD), and the IDA Pro client runs on the analysis system (Windows). The two communicate over the network, controlling the target program and exchanging debug information.

The FreeBSD system can run the linux_server debug server provided by IDA through the Linux binary compatibility layer. This server is responsible for monitoring target program execution, handling breakpoints, retrieving register and memory states, and transmitting debug information back to the IDA Pro client.

Preparing the Debug Server

First, on the Windows system, locate the linux_server file in the dbgsrv folder under the IDA installation path. This file is the 64-bit Linux debug server program provided by IDA, which can be run through FreeBSD's Linux compatibility layer.

Copy linux_server to the FreeBSD system, along with the target file to be remotely debugged. You can use WinSCP, SCP, or other file transfer tools.

View the debug server file details:

$ file linux_server
linux_server: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=ff98293848c412e3ef45ee78dac017464ac3059f, for GNU/Linux 3.2.0, stripped

Create a working directory on the FreeBSD system and place the files:

# mkdir -p /home/ykla/reverse
# cp linux_server /home/ykla/reverse/
# cp target /home/ykla/reverse/

Set execute permission for the debug server:

# chmod 755 /home/ykla/reverse/linux_server

Related file structure:

/home/ykla
└── reverse/ # Reverse engineering working directory
    ├── linux_server # IDA remote debug server
    └── target # Target file to debug

Starting the Debug Server

Start the debug server:

# ./linux_server
IDA Linux 64-bit remote debug server(ST) v9.3.31. Hex-Rays (c) 2004-2026
2026-05-24 13:55:31 Listening on :::23946 (my ip 192.168.179.128)...

After running, the debug server will listen on the default port, waiting for the IDA Pro client to connect.

Configuring the IDA Pro Client

Please use the 64-bit version of IDA and follow these steps.

Click "Debugger" in the top menu bar, then select "Run" from the menu, and select "Remote Linux debugger" from the submenu.

IDA Pro

IDA Pro

Fill in the following information in the debug configuration interface:

Field	Description	Example
Application	The file to debug	target
Directory	Full path to the debug file in the virtual machine	/home/ykla/reverse/
Hostname	IP address of the FreeBSD system	192.168.179.128

After configuration, connect to the debug server. Once the connection is successful, you can start debugging.

The server side will display the following information:

2026-05-24 14:01:05 [1] Accepting connection from ::ffff:192.168.179.1...

This indicates that the client (192.168.179.1) has connected to the server.

IDA Pro connected to debug server

You can now start analyzing the program.