I used to use netcat for Windows to help track down network connectivity issues. However these days my anti-virus software (Symantec - but I understand others display similar behaviour) quarantines netcat.exe as malware.

Are there any alternative applications which provide at least the following functionality:

• can connect to an open TCP socket and send data to it which is typed on the console
• can open and listen on a TCP socket and print received data to the console

?

I don't need the 'advanced' features (which are possibly the reason for the quarantining) such as port scanning or remote execution.

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8 Answers

ncat seems to be exactly what you're looking for. It's an implementation of netcat available on the official Nmap site with the port scanning feature removed. Doesn't raise any virus alerts either.

From the "Ncat Users' Guide":

Ncat is our modern reinvention of the venerable Netcat (nc) tool released by Hobbit in 1996. While Ncat is similar to Netcat in spirit, they don't share any source code. Instead, Ncat makes use of Nmap's well optimized and tested networking libraries. Compatibility with the original Netcat and some well known variants is maintained where it doesn't conflict with Ncat's enhancements or cause usability problems. Ncat adds many capabilities not found in Hobbit's original nc, including SSL support, proxy connections, IPv6, and connection brokering. The original nc contained a simple port scanner, but we omitted that from Ncat because we have a preferred tool for that function.

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This person ran into the exact same problem; read till the end for the version compiled without remote execution. I downloaded and extracted these on two systems running 'Symantec Endpoint Protection'. While the netcat on this page was removed and quarantined when run, the 'rodneybeede' version linked to near the end of the page tried to connect to the desired port, and wasn't quarantined.

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The quick answer here is to use the built in Telnet program from the CMD command line.

the command is...

telnet hostname.domain.com 80

The above example will connect you to the hostname on port 80. you can use it on just about any port you need to check out. This is extremely handy for troubleshooting SMTP and ESMTP issues.

12

I discovered that MobaXterm for Windows has the nc (netcat) command, as well as many other Unix commands, like ls, ps, and kill.

I wholeheartedly recommend MobaXterm, especially if you are familiar with both Unix and DOS. For me, there was nothing to install; it's just one executable that opens a terminal window in Windows that accepts many Unix commands. Since I frequently use both Unix and DOS and often use one to connect to the other, MobaXterm for Windows is an extremely useful tool for me.

(Sorry if this sounds like an advertisement; I don't work for nor am I affiliated with MobaXterm. A friend recently introduced it to me and it made certain tasks so much easier for me.)

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If you need netcat, you can whitelist netcat.exe in your anti-virus program.

You may also want to download a current version, which is called ncat and can be found in the nmap distribution.

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You can download Ncat - Netcat for the 21st Century. It seems to be a modern version of NCat, it is actively supported, and, most important, it had a 0/48 detection ratio at VirusTotal.

Portable version or from NMap Windows installer - disable anything else from the install wizard:

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Even if it seems otherwise, Wireshark is easy to use. You can setup it easily to listen to a specific port.

Another tool is nmap which again, I find easy to use. It will tell you much about open ports on a remote machine, so you can use it troubleshoot connectivity issues. Just nmap from command line, or from included gui interface.

Just give them a try.

7

There is now also separate 'ncat' static build available at