ポート 995 — POP3S (TCP)
What is Port 995?
SSL 上の安全な POP3。
This is a well-known port (0–1023) commonly used by core services like POP3S. · RFC 1939 (base protocol), RFC 2595 (STARTTLS extension)
When do you need Port 995 open?
Open on mail servers to allow encrypted POP3 email retrieval. Preferred over plain POP3 (port 110). Only needed if you host a mail server with POP3 access enabled.
Common uses and software
- Microsoft Outlook
- Mozilla Thunderbird
- Apple Mail
Security
POP3S encrypts the entire session. Ensure TLS 1.2 minimum with a valid certificate. Disable plain POP3 (port 110) to prevent clients from connecting without encryption. Consider migrating users to IMAPS (port 993) for better multi-device support.
Is Port 995 safe?
An open port increases your attack surface. Safety depends on how POP3S is configured.
Keep POP3S up to date with security patches. Require strong authentication and restrict access to the minimum necessary IP addresses.
Test connectivity for Port 995 on any host.
How to Open Port 995
To allow incoming connections to Port 995 (POP3S) from outside your network, configure your firewall and add a port forwarding rule on your router pointing to your device's local IP address.
Open Windows Defender Firewall → Advanced Settings → Inbound Rules → New Rule → Port → TCP → Specific local ports: 995 → Allow the connection → Name and save the rule.
netsh advfirewall firewall add rule name="Open Port 995" dir=in action=allow protocol=tcp localport=995sudo ufw allow 995/tcpsudo iptables -A INPUT -p tcp --dport 995 -j ACCEPTLog into your router (192.168.1.1 or 192.168.0.1) → Port Forwarding → Add a new rule: Protocol TCP, External port 995, Internal IP: your device's local IP, Internal port 995 → Save.
How to close Port 995
If you do not need POP3S, block this port in your firewall or router.
To block port 995 on Windows, run the following command in PowerShell or Command Prompt (as Administrator):
netsh advfirewall firewall add rule name="Block Port 995" dir=in action=block protocol=tcp localport=995sudo ufw deny 995/tcpsudo iptables -A INPUT -p tcp --dport 995 -j DROPRemove or disable any port forwarding rule for Port 995.
Frequently Asked Questions
What is Port 995 used for?▾
Port 995 is the default TCP port for POP3S. It is used by servers and applications that need to accept incoming connections for this service. Whether you need it open depends on whether you are actively running a POP3S server — if not, it should remain closed to reduce your attack surface.
Is Port 995 safe to keep open?▾
An open Port 995 increases your attack surface. If you are not actively running POP3S, close this port in your firewall and remove any port forwarding rules. If POP3S must be accessible, restrict access to known IP ranges, keep the service software updated with security patches, and use strong authentication.