Netcat – The swiss army knife of networking

seriously, I was introduced to socat about 5 months ago... blew my mind. netcat is good and I still use it to quickly send custom GET requests, but socat is like a swiss-army knife containing many swiss-army knives. It even forwards unix-domain sockets and doesn't necessarily need root permissions like iptables.

Agreed. If netcat is the swiss-army knife of network tools, socat is the complete utility belt. I discovered socat because netcat simply wouldn't bend in all the ways I needed it to. There is NOTHING ad-hoc network related that I haven't been able to perform with socat.

I connected an SNMP monitoring system using two socats and an ssh tunnel. One socat to forward UDP over TCP to the locally encrypted port, and another to take it off on the other side and forward it to a local SNMP listener. It was a for a control system we were building that could monitor temperatures and control fan speeds in a computer cooling system. We ran it across several states in the US, and it was just to get an early demo of how the system would work before hardware was more locally available and the damned thing worked...

This made a lot of people very happy and it was really crazy to be on the phone with the other folks and have them rev up the fans in our lab via SNMP through this channel.

/me too/

I like it (tar|nc) as a quick alternative when moving data to or from low performance devices such as Android phones. Rsync/SSH really burns a lot of power for encryption. Makes a full x GB Backup much faster to pipe it through netcat (or bashs /dev/tcp if available).

If that's your use case then have a look at ncp: http://www.fefe.de/ncp/

From the site: '"ncp" is a utility for copying files in a LAN. It has absolutely no security or integrity checking, no throttling, no features, except one: you don't have to type the coordinates of your peer.'

This is what everyone should be using instead of 'nc'. SSL, SCTP, IPv6, proxying, hex dump, keep open, waits, and more.

I wouldn't call 'socat' a swiss army knife. More like a tool shed. But it is very handy at times.

I really don't see how Apache vs Nginx will give you that much performance increase. The majority of the processing time for a request is in the backend (rendering, compiling, db calls, &c). Improved caching would give much better performance gains than just switching a server without any other improvements.

and it supports sctp.

There are two kinds of operating systems, those that people use and those that people don't complain about.

It should be noted that rlwrap works on all programs that use readline. I've used it when starting out with programming in SML and getting annoyed at the missing arrow-up command history.

Actually the netcat shipped on most/all common Linux distributions (though IIRC, frustratingly not Cygwin which has a more limited one without the SOCKS features) is the one from OpenBSD.

But obviously the article was written from the perspective of "Fun commands available on Linux". I'm all for giving proper credit where it is due, but it's asking a little too much to expect that every newbie tutorial is going to inflict a full software genealogy on the poor reader...

This is basically #7, and I found it particularly handy when Ghost barfed on my source image.

Since we had an entire lab to clone to, we combined dd, netcat, and tee to just daisy chain the data out. It worked _magically_.

Do you mean to use >redirect, or did you mean |pipe?

In the situations where nc is useful then scapy is probably not an option. Nc, dd, and a few others are almost always present and great when you are in a real bind... something went wrong in a network install in pxelinux, and you want to copy off dumps or config files, or copy on a missing file. Otherwise, there are better ways to do most of the things mentioned in the article, most involving scp.

EDIT: the number of responses to this article happily highlighting the lack of security in netcat just terrifies me.

EDIT2: Ah, I see what you were saying (and scapy is an awfully cool library). It was just a convenient place for me to highlight was I didn't think was highlighted enough in the article: nc can do neat things, but not much that can't be accomplished better with other tools - its big advantage is that it's almost always present, even if ssh/scp, rsync, netstat, wget/curl, etc are not. Like using cat + sed as a text editor :)

For the simple task of moving bytes through a tcp connection (what the article is about) netcat will be fine.

Socat allows you to use raw interfaces, or fifos, SSL, proxies, serial ports,... as one or both end points. E.g. you can forward arbitrary tcp connections (tcp relay;) but also connect stdin/stdout if a program to a serial port... just very, very, very versatile.

http://www.dest-unreach.org/socat/doc/socat.html

Plenty of other previous mentions here for you to peruse: https://www.hnsearch.com/search#request/submissions&q=ne...