Description
Sophos SG 125
The Sophos SG 125 is a compact network security appliance from the Sophos SG Series. It was designed to deliver firewall, VPN, intrusion prevention and other security functions in a desktop form factor.
Sophos positioned the SG 125 and related SG 100 Series models for small businesses, branch offices, remote locations and retail environments. The SG 125 provides eight Gigabit Ethernet copper ports and was specified at up to 3.1 Gbps firewall throughput.
Network Security
The appliance combines several network security functions within the Sophos UTM platform. Published specifications include up to 500 Mbps VPN throughput, 750 Mbps IPS throughput and 200 Mbps antivirus proxy throughput for the SG 125 in the earlier SG Series documentation.
This combination allowed organizations to deploy firewall and security controls through a single appliance rather than maintaining separate devices for each function.
Connectivity
The SG 125 provides eight fixed Gigabit Ethernet copper ports. This interface configuration allows the appliance to connect multiple network segments and infrastructure components while retaining a compact physical design.
The SG 125 should not be confused with the SG 125w, which adds integrated wireless networking. The standard SG 125 is the wired model.
Deployment
The desktop form factor makes the SG 125 suitable for locations where a compact appliance is preferred. Sophos documentation describes the SG 125 class as providing 1U performance in a desktop form factor and identifies small businesses, branch offices and remote locations as target environments.
Lifecycle Consideration
The SG 125 is now a legacy product. Sophos announced that Sophos UTM/SG reached end of life on June 30, 2026. Sophos also states that the SG 125 maps to the XGS 128 as its equivalent migration model.
For this reason, organizations considering an SG 125 today should verify availability, licensing, support status and intended deployment requirements before purchasing. For a new production deployment, the current Sophos migration guidance should be considered alongside the SG 125’s historical specifications.
Selection Guide
For Existing SG 125 Deployments
Confirm the exact SG 125 hardware revision before assessing performance, compatibility or replacement requirements. Sophos documentation and regulatory records identify SG 125 revisions, including revision 3.
For Network Connectivity
The SG 125 provides eight Gigabit Ethernet copper ports. Review the number of required WAN, LAN, DMZ and segmented interfaces before selecting or replacing the appliance.
For VPN Requirements
The published SG 125 VPN throughput is up to 500 Mbps. Actual performance depends on configuration, traffic characteristics and enabled security functions.
For Security Processing
Review the published firewall, IPS and antivirus throughput figures together rather than considering firewall throughput alone.
For Replacement Planning
Sophos’ published migration path maps:
Sophos SG 125 → Sophos XGS 128.
Installation Notes
The SG 125 is designed as a compact desktop appliance. Install the unit on a stable surface with adequate ventilation and allow sufficient clearance around the appliance.
Connect the required Gigabit Ethernet interfaces according to the network design, then connect the power supply and management interfaces as required.
If rack installation is required, verify the correct model-specific mounting hardware. Sophos previously listed rackmount kits for SG desktop models as separately available accessories, although SG-specific desktop rackmount kits were discontinued for sale after June 30, 2024.
For an existing appliance, always follow the documentation for the exact SG 125 revision.
Best Practices
- Verify the exact SG 125 hardware revision before deployment.
- Confirm current software and support status before relying on an existing SG appliance.
- Document WAN, LAN, DMZ and other interface assignments.
- Maintain appropriate airflow around the appliance.
- Use secure administrative credentials and restrict management access.
- Back up configuration information before major changes.
- Check Sophos lifecycle documentation when planning long-term deployment.
- Consider the XGS 128 migration path when replacing an SG 125.
- Do not assume historical throughput figures represent current-generation firewall performance.
Sophos states that SG Series hardware is no longer supported by Sophos Firewall 21.0 and later, reinforcing the need to check software compatibility when evaluating older SG hardware.
Benefits for IT Teams
The Sophos SG 125 can simplify network security by consolidating firewall, VPN and intrusion prevention functions into one appliance.
Its eight Gigabit Ethernet ports provide a straightforward interface layout for small network environments, while the compact chassis can be deployed where rack space is limited.
For organizations that already have SG 125 appliances, understanding the hardware revision, software compatibility and lifecycle position is particularly important. Sophos’ current migration guidance provides an XGS 128 path for SG 125 deployments.
Main Benefits
Multi-Function Network Security
The Sophos SG 125 combines firewall, VPN, IPS and other UTM capabilities in one appliance.
Benefit: Reduce the need to deploy separate security appliances for different network protection functions.
Multiple Gigabit Interfaces
Eight fixed Gigabit Ethernet copper ports provide connectivity for multiple network segments and devices.
Benefit: Support practical LAN, WAN and segmented network deployments.
Compact Deployment
The desktop form factor provides a smaller alternative to conventional 1U rack appliances.
Benefit: Suitable for offices and branch locations where rack space is limited.
VPN Connectivity
The SG 125 provides published VPN throughput of up to 500 Mbps.
Benefit: Support secure connections between networks and remote locations.
Intrusion Prevention
With published IPS throughput of up to 750 Mbps, the SG 125 can provide network traffic inspection as part of its security configuration.
Benefit: Add intrusion prevention capabilities alongside firewall protection.
Established Sophos Platform
The SG 125 belongs to a long-running Sophos security appliance family with documented migration options to newer Sophos hardware.
Benefit: Existing SG 125 deployments can be assessed against the published XGS migration path rather than treated as an unsupported upgrade scenario. Sophos maps the SG 125 to the XGS 128.
Typical Use Cases
1. Small Business Network Security
The SG 125 was designed for small-business environments requiring an integrated firewall and network security appliance.
2. Branch Office Protection
Its compact desktop form factor makes it suitable for branch offices where multiple network interfaces and centralized security controls are required.
3. Remote Office Connectivity
VPN capabilities allow the appliance to participate in secure connections between remote locations and central networks.
4. Network Segmentation
The eight Gigabit Ethernet interfaces can be used to connect different network segments, depending on the deployment configuration.
5. UTM Security Deployment
The SG 125 was designed to consolidate multiple security services within a single Sophos UTM appliance.
6. Existing Sophos Infrastructure
Organizations that already operate SG 125 appliances can use the model’s specifications and Sophos’ published migration path when planning replacement with newer Sophos hardware.
Who Should Buy Sophos SG 125?
The Sophos SG 125 is primarily relevant to organizations looking for existing, replacement or legacy SG Series hardware, rather than customers starting a new Sophos Firewall deployment.
It may be relevant for:
- Organizations maintaining an existing SG 125 environment
- Businesses looking for compatible replacement hardware
- IT teams managing legacy Sophos infrastructure
- Labs or testing environments where legacy SG hardware is appropriate
- Organizations evaluating migration from SG 125 to XGS 128
For new production deployments, the SG 125’s lifecycle should be considered carefully because Sophos UTM/SG reached end of life on June 30, 2026.
Related Categories
Explore related product and service pages for:
- Sophos Firewalls
- Sophos XGS 128
- Sophos SG Series
- Sophos Firewall
- Sophos Firewall Accessories
- Sophos Rackmounts
- Sophos Network Security Appliances
- Sophos UTM Migration
The SG 125’s published Sophos migration path is XGS 128, making the XGS 128 an important related product for replacement planning.
Frequently Asked Questions
What is the Sophos SG 125?
The Sophos SG 125 is a desktop network security appliance from the Sophos SG Series. It was designed for firewall, VPN, IPS and other UTM security functions in small-business and branch-office environments.
How many ports does the Sophos SG 125 have?
The SG 125 has 8 fixed Gigabit Ethernet copper ports.
What is the firewall throughput of Sophos SG 125?
Sophos published a firewall throughput of up to 3.1 Gbps for the SG 125.
What is the VPN throughput of Sophos SG 125?
The published VPN throughput for the SG 125 is up to 500 Mbps. Actual performance depends on configuration and traffic conditions.
What is the IPS throughput of Sophos SG 125?
Sophos’ SG Series specifications list up to 750 Mbps IPS throughput for the SG 125.
Does Sophos SG 125 have built-in Wi-Fi?
The standard SG 125 is a wired appliance. Sophos also produced the SG 125w, which included integrated wireless networking.
Is Sophos SG 125 still supported?
The SG Series is now a legacy platform. Sophos announced the end of life of Sophos UTM/SG on June 30, 2026. In addition, Sophos Firewall 21.0 and later do not support SG Series hardware.
What is the replacement for Sophos SG 125?
Sophos’ published migration path maps the SG 125 to the XGS 128.
Can Sophos SG 125 still be used?
Existing SG 125 hardware may remain relevant in legacy environments depending on its software, licensing and support circumstances. However, organizations should consider the June 30, 2026 SG/UTM end-of-life milestone when planning continued use.
Is Sophos SG 125 suitable for a new deployment?
Because the SG/UTM platform reached end of life on June 30, 2026, the SG 125 should generally be evaluated as legacy hardware rather than as a current-generation Sophos Firewall platform. Sophos provides an XGS 128 migration path for SG 125 customers.
What is the difference between SG 125 and SG 125w?
The standard SG 125 is the wired version. The SG 125w adds integrated wireless networking, with Sophos documentation specifying 802.11a/b/g/n/ac wireless for the 125w variant.
