Port 110: POP3
Downloads mail from a mailbox, unencrypted. Use POP3S on 995 instead, so passwords are not sent in clear text.
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Port Lookup
Port 110 at a glance
Port110
ProtocolTCP
ServicePOP3
Open to the Internet?Only to addresses that need it
See What Is Listeningss -lntup | grep ':110 '
Test From Outsidenc -zv your-server 110
Block with UFWufw deny 110/tcp
Block with nftablesnft add rule inet filter input tcp dport 110 drop
POP3 uses TCP port 110. Downloads mail from a mailbox, unencrypted.
Use POP3S on 995 instead, so passwords are not sent in clear text.
Allow port 110 only from the addresses that need it: your office, a VPN or a bastion host. The firewall rule generator builds those rules for nftables, iptables and UFW.
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 110 used for?
POP3. Downloads mail from a mailbox, unencrypted.
Is it safe to open port 110?
Only to addresses that need it. Use POP3S on 995 instead, so passwords are not sent in clear text.
How do I check if port 110 is open?
On the server, ss -lntup | grep ':110 ' shows what is listening. From another machine, nc -zv your-server 110 shows whether the firewall lets it through.
How do I block port 110?
With UFW: ufw deny 110/tcp. With nftables, add a drop rule for dport 110 in your input chain.
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