top of page
Blocked Internal Port List
Find out which ports are automatically blocked on our network and why.
Ports on the internet are like virtual passageways where data can travel. All information on the internet passes through ports to get to and from computers and servers. When a certain port is known to cause vulnerability to the security and privacy of your information, MCF blocks it to protect you.
Port | Transport | Protocol | Direction | Reasons For Blocking | IP Version |
|---|---|---|---|---|---|
1080 | UDP | SSDP | Both | Port 1900 is vulnerable to DoS attacks. | IPv4/IPv6
|
1900 | TCP | SOCKS | Downstream | Port 1080 is vulnerable to, among others, viruses, worms and DoS attacks. | IPv4/IPv6
|
547 | UDP | DHCPv6 | Downstream | UDP Port 547, which is used to obtain dynamic Internet Protocol (IP) address information from our dynamic host configuration protocol (DHCP) server, is vulnerable to malicious hacks. | IPv6 |
520 | UDP | RIP | Both | Port 520 is vulnerable to malicious route updates, which provides several attack possibilities. | IPv4 |
445 | TCP | MS-DS, SMB | Both | Port 445 is vulnerable to attacks, exploits and malware such as the Sasser and Nimda worms. | IPv4/IPv6
|
161 | UDP | SNMP | Both | SNMP is vulnerable to reflected amplification distributed denial of service (DDoS) attacks. | IPv4/IPv6
|
135-139 | TCP/UDP | NetBios | Both | NetBios services allow file sharing over networks. When improperly configured, ports 135-139 can expose critical system files or give full file system access (run, delete, copy) to any malicious intruder connected to the network. | IPv4/IPv6
|
67 | UDP | BOOTP, DHCP | Downstream | UDP Port 67, which is used to obtain dynamic Internet Protocol (IP) address information from our dynamic host configuration protocol (DHCP) server, is vulnerable to malicious hacks. | IPv4 |
25 | TCP | SMTP | Both | Port 25 is unsecured, and Botnet spammers can use it to send spam. This does not affect MCF Connect usage. We recommend learning more about configuring your email settings to Comcast email to use port 587. | IPv4/IPv6
|
0 | TCP | N/A | Downstream | Port 0 is a reserved port, which means it should not be used by applications. Network abuse has prompted the need to block this port.
| IPv4/IPv6
|
bottom of page