Common attacks and weaknesses
- Brute force and password spraying against mailboxes.
Port 995: POP3S
POP3 over TLS.
995
How POP3S works
EmailThe mail client connects to port 995 to download or sync the messages waiting in the mailbox. Everything is encrypted: someone on the path only sees unreadable bytes.
- Transport
- TCP · UDP
- Exposure risk
- 3/10 moderate if reachable from the Internet
- Encryption
- EncryptedTLS or built-in crypto
- IANA status
- Assigned1 registered service
- Range
- Well-known (0-1023)
- Category
Is port 995 dangerous?
How to secure it
- Rate-limit logins and require MFA or app passwords.
IANA registry entries for port 995
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| pop3s | 995 | TCP, UDP | POP3 over TLS protocol | RFC 8314 | 2017-12-12 |
// source: IANA service name and port number registry
Which program uses port 995, and is it reachable?
Linux
sudo ss -ltnup 'sport = :995' # process listening on 995
sudo lsof -nP -i :995macOS
sudo lsof -nP -i :995
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 995 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 995 netstat -ano | findstr :995
From another machine
nmap -p 995 -sV <host> sudo nmap -sU -p 995 <host> nc -zv <host> 995
Block it in the firewall
sudo ufw deny 995/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 995" -Direction Inbound -LocalPort 995 -Protocol TCP -Action Block # Windows
What is port 995 used for?
POP3 over TLS.
Is port 995 TCP or UDP?
Port 995 is registered for TCP and UDP. In practice the service mostly uses TCP.
Is it safe to open port 995?
It is rated 3/10 (moderate) when exposed to the Internet. Brute force and password spraying against mailboxes. Rate-limit logins and require MFA or app passwords.
How do I check if port 995 is open?
On Linux run "ss -ltnup 'sport = :995'", on macOS "lsof -nP -i :995", and on Windows "netstat -ano | findstr :995" to see the local process. From another machine, "nmap -p 995 <host>" shows whether it is reachable.