Use seccomp to limit which system calls a process can make, and Linux capabilities to remove privileged operations it does not need. Together they can reduce the kernel-facing options and authority available after a process is compromised—but neither is a complete sandbox. Build policy around the application’s required behavior, validate it on the target architecture, and combine it with other isolation controls.
What each control limits
| Control | What it restricts | Configuration unit | Key limitation |
|---|---|---|---|
| seccomp | System calls the process may attempt, based on filter rules and syscall metadata | A filter attached to a process; filters can be layered and inherited | It reduces syscall exposure but is not a complete sandbox. The Linux kernel documentation says, “System call filtering isn’t a sandbox.” Linux Kernel documentation: Seccomp BPF |
| Linux capabilities | Specific privileged operations otherwise associated with superuser authority | Distinct per-thread privilege attributes | Capabilities divide privilege; they do not, by themselves, isolate all process behavior. Linux man-pages: capabilities(7) |
Think of seccomp as limiting the kernel entry points a process can use, and capabilities as limiting certain privileged actions it can perform. A syscall filter does not replace least-privilege permissions, and capability reduction does not remove unnecessary syscall paths. Applying both can constrain different dimensions of a compromised process’s options.
Build a policy around the workload
1. Identify required behavior first
Start with the application’s actual functions and the system calls needed to perform them. Then reduce the allowed syscall set to that behavior. The kernel describes seccomp as useful for applications that need only a subset of the syscall interface exposed to user space. There is no universal allowlist: requirements vary with the application, runtime, kernel, and architecture.
2. Install the filter with the required privilege condition
Before an unprivileged process installs a seccomp filter, set no_new_privs. Alternatively, the caller must have CAP_SYS_ADMIN in its user namespace. The no_new_privs condition prevents a filter from being applied in a way that could let a child gain greater privilege. Check the target system’s kernel configuration and architecture support before relying on a specific seccomp interface. Linux Kernel documentation: Seccomp BPF Linux man-pages: seccomp(2)
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
3. Decide whether child processes must stay constrained
When the policy allows fork or clone and execve, children inherit installed filters and the syscall ABI constraint. Account for this when an application launches helpers: inheritance can preserve restrictions across process creation and execution, but it also means a helper requiring additional syscalls may fail under the inherited policy. Linux Kernel documentation: Seccomp BPF
4. Check architecture as well as syscall number
Filter logic that examines a syscall number must also check the architecture value. The kernel documentation warns that checking the number alone is unsafe. Validate the policy for the architecture on which it will run; do not assume syscall numbering or ABI details are interchangeable across architectures. Linux Kernel documentation: Seccomp BPF
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Reduce capabilities to the minimum required
Review the application’s capabilities individually and retain only those needed for its legitimate operation. The capability model breaks superuser privilege into separately controlled units, so avoiding an unnecessary capability can remove a meaningful class of privileged actions.
CAP_NET_RAWis an example of a distinct permission with concrete consequences; assess whether the workload actually requires it.CAP_SYS_ADMINis broad and overloaded. The capabilities manual advises kernel developers to avoid selecting it when a narrower capability can be used. Avoid granting it merely for convenience when a more limited design will work.
Which capabilities to retain depends on the application and its execution environment. These general references do not establish a safe drop list or container configuration for a particular workload. Linux man-pages: capabilities(7)
Recommended Free Tools
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
Validate the combined policy before deployment
- Confirm the target: record the relevant kernel, architecture, application behavior, and runtime conditions. Check that the required seccomp support is available.
- Draft the syscall policy: allow only the calls the workload needs, and ensure the filter checks architecture as well as syscall number.
- Set the installation condition: use
no_new_privsfor unprivileged filter installation, or confirm the caller hasCAP_SYS_ADMINin its user namespace. - Review process creation: determine whether child processes and executed helpers should inherit the filter, and test their required behavior under that policy.
- Review capabilities separately: remove permissions the application does not need, paying particular attention to broad grants such as
CAP_SYS_ADMIN. - Test representative behavior: exercise normal operations and helper processes under the exact target architecture and deployment setup. Watch for application failures caused by blocked syscalls, then adjust only when a required behavior is understood.
- Keep other isolation layers: pair seccomp and capability reduction with the other hardening controls appropriate to the environment, including an LSM where suitable.
Understand what these controls do not guarantee
Seccomp narrows the syscall interface; capabilities narrow selected privileged authority. Neither claim establishes complete application isolation or prevents every harmful outcome from a compromised process. The kernel documentation explicitly notes that other hardening techniques, and potentially a Linux Security Module (LSM), may be needed to address logical behavior and information flow. Treat these controls as layers in a broader design, not as proof that a process is safe if exploited. Linux Kernel documentation: Seccomp BPF Linux man-pages: capabilities(7)
Quick Recap
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
