Port Filtering With BrowseControl
BrowseControl is a host-based web filtering and port blocking software for filtering TCP/UDP network ports on endpoint devices. Effortlessly block ports that are unused and exploitable to reduce the attack surface of your network.
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Port Filter to Block Unused Network Ports
- Deny by Default: All ports should be closed by default unless there is a documented, reviewed, and approved business case.
- Defense in Depth: Combine BrowseControl’s host-based port filtering with a perimeter-based firewall for a defense-in-depth approach.
- Risk Assessment: Any port can be exploited by an attacker. Blocking unused ports reduces the attack surface of your network.
Why Block Ports?
Malicious hackers can use port scanning tools to discover open ports in your network.
Once they find an available port number they can use it to search for potential vulnerabilities that they can use to gain unauthorized access into your network.
By proactively blocking unused ports with port blocking software you can reduce the attack surface available to threat actors and improve network security by making the filtered port inaccessible.
What is Port Filtering?
The internet and applications use predetermined TCP/UDP ports to transmit network protocol packets (data).
Port filtering is the practice of allowing or blocking (opening/closing) network packets into or out of a device or the network based on their port number.
Using a port filter allows administrators to restrict specific operations such as file transfers through FTP and torrents. With the filtered port inaccessible you can reduce the attack surface of your network.
Recommended Ports to Block
While any port number can be potentially exploited, there are some ports that are known security risks.
If a Deny-by-Default approach isn’t feasible for your organization, try these recommended ports to block in your port filter.
- Internet Relay Chat (IRC): Botnets can use IRC to communicate with infected machines. Close the port range 6660 – 6669 to block IRC.
- Telnet: Telnet is not a secure protocol and is unencrypted. Block port 23 to restrict access to it
- Memorable Numbers: Some malware authors use easy-to-remember numbers such as 234, 6789, 1111, 666, and 8888
- File Transfer Protocol (FTP): FTP is used to transfer computer files from a server to a client on a computer network. Block port 21 to restrict this data egress point on client computers.
What Ports Need to Be Left Open?
Port requirements are unique to each organization and its networks. The specific ports required by business applications will evolve over time as well. Here are some ways to determine which ones you need to keep open.
- Product Documentation: Consult the manuals of any software and hardware used in your organization and see if they require specific ports to be left open.
- Netstat & Resource Monitor: Use a netstat command and Windows resource monitor to identify ports that are currently in use by a specific computer.
- Trial & Error: If you only use internet-connected computers and have no other special needs, try blocking all ports except for port 80 (HTTP internet) and port 443 (HTTPS internet). Test all services and applications in your organization to see if there are any connection issues and monitor IT support tickets for any unforeseen issues.
- Research Ports: If you need to perform special actions such as file transfers over FTP or hosting your own email servers you’ll need to consult this list to see the ports that are required by each of them.
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Fully functional. Easy to use. Install in minutes.
BrowseControl Web Filtering Features
Internet ON/OFF
One click to completely block
users from browsing the web
URL Filter
Allowed list or Blocked list for
specific URLs
Category Filtering
Block websites based on specific web content categories
Internet Scheduler
Schedule internet use policies for specific times of the day
Safe Search
Search engine filters prevent explicit results in search engines
Internet Quota
Set a time-based quota for
internet browsing
Download Filter
Block files from being downloaded from the internet
Port Filter
Close unused and high-risk
TCP/UDP ports
Customize Message
Display a customized warning
message on blocked websites
Application Blocker
Block specific Windows
applications from launching
Timer
Allocate specific time for your
users to access the Internet
Stealth Mode
Restrict internet use without
altering users
Centralized Console
Manage all your users from the
centralized console with Active
Directory import or syncing
Platform Security
Protect your CurrentWare console
with 2FA, passwords, privilege
management, and more
Offsite Management
Extend onsite Internet usage
policies to laptops running outside
the corporate network
SQL Server Supported
Database scaled for enterprise and
large business operations using
Microsoft SQL Server
Try BrowseControl for Free
Fully functional. Easy to use. Install in minutes.