Port 445: SMB
Windows file sharing. WannaCry and NotPetya spread through exposed SMB. Most ISPs block it; never open it to the internet.
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Port Lookup
Port 445 at a glance
Port445
ProtocolTCP
ServiceSMB
Open to the Internet?No, keep it on a private network
See What Is Listeningss -lntup | grep ':445 '
Test From Outsidenc -zv your-server 445
Block with UFWufw deny 445/tcp
Block with nftablesnft add rule inet filter input tcp dport 445 drop
SMB uses TCP port 445. Windows file sharing.
WannaCry and NotPetya spread through exposed SMB. Most ISPs block it; never open it to the internet.
If ss shows something listening on port 445 on a public address, bind it to 127.0.0.1 or a private interface in the service's own configuration, and drop the port in the firewall as well.
Other Ports
20 FTP Data21 FTP22 SSH23 Telnet25 SMTP53 DNS67 DHCP Server80 HTTP110 POP3123 NTP143 IMAP161 SNMP389 LDAP443 HTTPS445 SMB465 SMTPS514 Syslog587 Mail Submission853 DNS over TLS993 IMAPS995 POP3S1194 OpenVPN1433 Microsoft SQL Server1900 SSDP / UPnP2049 NFS2083 cPanel (SSL)2087 WHM (SSL)3306 MySQL / MariaDB3389 RDP3478 STUN / TURN5060 SIP5432 PostgreSQL5900 VNC6379 Redis8006 Proxmox VE8080 HTTP Alternate8443 HTTPS Alternate11211 Memcached25565 Minecraft27017 MongoDB51820 WireGuard
Questions
What is port 445 used for?
SMB. Windows file sharing.
Is it safe to open port 445?
No, keep it on a private network. WannaCry and NotPetya spread through exposed SMB. Most ISPs block it; never open it to the internet.
How do I check if port 445 is open?
On the server, ss -lntup | grep ':445 ' shows what is listening. From another machine, nc -zv your-server 445 shows whether the firewall lets it through.
How do I block port 445?
With UFW: ufw deny 445/tcp. With nftables, add a drop rule for dport 445 in your input chain.
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