Check whether your device is exposed to incoming connections from the internet. If you use a VPN, this test checks the VPN’s public IP address.
run
Options
Search for references
Find saved network results that mention a domain name or IP address.
Host
IP or domain (required)
Related arguments and description
Find hosts that appear alongside an IP address or domain in cached command results.
Host
IP or domain (required)
Subdomains arguments and description
Find known subdomains in cached command results. This searches the cache and does not perform a live scan.
Host
Domain (required)
Nslookup arguments and description
NSLOOKUP is a programm for querying NS server for a specified domain. This tool is commonly used for detecting the IP address of the domain (A record), but can be used for receiving other NS records. It is very similar to DIG command. Unlike DIG, NSLOOKUP is based on its own resolver library.
Host
IP or domain (required)
NS server
DNS server IP or domain (optional)
Type
Port
-port=number (server port, default 53)
Debug
Debug2
Ping arguments and description
PING is the network command, which lets you check whether or not the host is alive and responding. The special protocol ICMP is used for pinging. See RFC 792 for ICMP protocol details. You can find the command arguments below.
Host
IP or domain (required)
Protocol
Packet size
-s number (default 56)
Map IP
MTU
Timestamp
Whois arguments and description
WHOIS searches Whois servers for the object (domain or IP). The special WHOIS protocol is used for querying the Whois servers. See RFC 3912 for the protocol specification. This command is available on all linux systems and has a lot of arguments. The most important argument is host address. See the arguments decription below.
Host
IP or domain (required)
Host arguments and description
HOST is a DNS lookup utility. You can use it to convert names to IP addresses and vice versa. It is similar to DIG and NSLOOKUP. This command is available on all linux distributives. There are several arguments. You can find decription of the arguments below.
Host
IP or domain (required)
NS server
DNS server IP or domain (optional)
Protocol
Type
All
Verbose mode
Traceroute arguments and description
TRACEROUTE is the network diagnostic command. This command tracks the route packets taken from an IP network on their way to a given host. ICMP or UDP packets are used. See the command arguments below.
Host
IP or domain (required)
Fragmentation
ICMP
TCP
Map IP
Protocol
Port
--udp=number (UDP destination port)
Geoiplookup arguments and description
GEOIPLOOKUP lets you detect the location of a host. A preparsed WHOIS database is used for detecting the location of IP or domain. There are a lot of independent geoip databases in the Internet, so the same host can have different locations in those databases. GEOIPLOOKUP is not a built-in Linux command. The command has only one argument - host address.
Host
IP address (required)
Dig arguments and description
The DIG command is a part of BIND package, available on all linux distributives. It is used for querying Domain Name Servers (DNS) using standard operating system libraries and display answers from these DNS servers. Domain Information Groper (DIG) is useful for troubleshooting DNS issues. You can find DIG arguments below.
Host
IP or domain (required)
NS server
@server (optional)
Type
Trace
Tcp
Ignore
AA only
AD flag
CD flag
Show class
Show TTL
Answer
Comments
Recurse
Short
Cmd
Identify
Stats
Authority
Additional
All
Multiline
One SOA
Fail
Best effort
DNSSEC
EDNS ID request
Why might an open port be a concern?
An open port means that a device may accept incoming connections. Personal computers commonly block all incoming ports because they usually do not need them. An open port that is not properly secured or maintained may expose the device to attackers. Open ports may also reveal that the public IP address belongs to a VPN server, making VPN use detectable.
Why should I check for open ports?
It is important to know which ports are open so you understand what services and information your device exposes publicly. Common ports are associated with well-known services, and attackers may use this information to identify and target the device.
What ports are included in the test?
The test checks the following commonly used ports.
21 FTP (File Transfer Protocol command channel)
22 SSH (Secure Shell protocol and secure file transfers)
23 Telnet (Unencrypted application protocol)
25 SMTP (Simple Mail Transfer Protocol used by mail servers)
53 DNS (Domain Name System protocol used by public resolvers)
80 HTTP (Hypertext Transfer Protocol used by public web servers)