netcat

trying to send UDP packets using Netcat nc -u 127.0.0.1 1234 And using tcpdump to see actual packets tcpdump -i any -vv -n udp dst port 1234 In theory the UDP packet size can be about 64K, however when I'm sending a message with size bigger than 2048 the Netcat splits the data and sends in 2 separate UDP packets. For example if I send the following long string

1，端口扫描 nc -z -v -n 172.31.100.7 21-25 2，聊天 Server： nc -l 1567 Client： nc 172.31.100.7 1567 3，文件传输 Server： nc -l 1567 < file.txt Client： nc -n 172.31.100.7 1567 > file.txt 4，目录传输 发送一个文件很简单，但是如果我们想要发送多个文件，或者整个目录，一样很简单，只需要使用压缩工具tar，压缩后发送压缩包。 如果你想要通过网络传输一个目录从A到B。 Server $tar -cvf – dir_name | nc -l 1567 Client $nc -n 172.31.100.7 1567 | tar -xvf - 来源： https://www.cnblogs.com/chuangcc/p/11963851.html

I have a project I'm working on, where a piece of Hardware is producing output that is continuously being written into a textfile. What I need to do is to stream that file as it's being written over a simple tcp/ip connection. I'm currently trying to that through simple netcat, but netcat only sends the part of the file that is written at the time of execution. It doesn't continue to send the rest. Right now I have a server listening to netcat on port 9000 (simply for test-purposes): netcat -l 9000 And the send command is: netcat localhost 9000 < c:\OUTPUTFILE So in my understanding netcat

# 1.安装gcc yum install -y gcc #2.下载 cd /usr/local/src/ wget http://sourceforge.net/projects/netcat/files/netcat/0.7.1/netcat-0.7.1.tar.gz # 3.解压 tar -zxvf netcat-0.7.1.tar.gz -C /usr/local # 4.编译的时候用来指定程序存放路径 cd /usr/local/netcat-0.7.1 ./configure --prefix=/usr/local/netcat make && make install # 5.添加配置 vim /etc/profile export NETCAT_HOME=/usr/local/netcat export PATH= $PATH: $NETCAT_HOME/bin source /etc/profile 此 处 的 / u s r / l o c a l / n e t c a t − 0.7.1 / 相 当 于 源 码 文 件 ， 安 装 成 功 的 文 件 是 / u s r / l o c a l / n e t c a t ， 这 里 可 以 将 / u s r / l o c a l / n e t c a t − 0.7.1 / 删 除 rm -rf

I am trying to use netcat to simulate a NAT traversal protocol. I have one instance that is listening for UDP packets on port 6666, as so: nc -ul 6666 In another terminal window, I am trying to periodically send a UDP packet from port 6666 (to open the return path on my router. this would be in a script that repeats every 20 seconds to re-open the port) nc -u -p6666 mypinghost.com 4444 The problem is netcat fails on this ping call with the message: nc: bind failed: Address already in use Which implies that the listener having bound to port 6666 is blocking another process from sending from

目录 nc 命令 一、简介 二、案例 1、端口扫描 2、聊天 3、文件传输 4、目录传输 5、加密网络发送的数据 6、流视频 7、克隆一个设备 8、打开一个shell 9、反向shell 10、指定端口 11、指定源地址 三、man手册 nc 命令 一、简介 netcat所做的就是在两台电脑之间建立链接并返回两个数据流，在这之后所能做的事就看你的想像力了。你能建立一个服务器，传输文件，与朋友聊天，传输流媒体或者用它作为其它协议的独立客户端。 二、案例 1、端口扫描 端口扫描经常被系统管理员和黑客用来发现在一些机器上开放的端口，帮助他们识别系统中的漏洞。 $nc -z -v -n 172.31.100.7 21-25 可以运行在TCP或者UDP模式，默认是TCP，-u参数调整为udp. z 参数告诉netcat使用0 IO,连接成功后立即关闭连接， 不进行数据交换(谢谢@jxing 指点) v 参数指使用冗余选项（译者注：即详细输出） n 参数告诉netcat 不要使用DNS反向查询IP地址的域名 这个命令会打印21到25 所有开放的端口。Banner是一个文本，Banner是一个你连接的服务发送给你的文本信息。当你试图鉴别漏洞或者服务的类型和版本的时候，Banner信息是非常有用的。但是，并不是所有的服务都会发送banner。 一旦你发现开放的端口，你可以容易的使用netcat

I'm trying to simultaneously save the output from a tmux pane to file and stream it using netcat. What works: tmux pipe-pane -o -t "server" "tee -a '/home/csgoserverp/test.txt'" echo -n "Hello World" | tee -a '/home/me/text.txt' | nc -4u -w1 0.0.0.0 9999 What does not work: tmux pipe-pane -o -t "server" "nc -4u -w1 0.0.0.0 9999" tmux pipe-pane -o -t "server" "tee -a '/home/me/test.txt' | nc -4u -w1 0.0.0.0 9999" Any help would be appreciated. I read somewhere that ncat is better than netcat and for reasons unknown using ncat works: tmux pipe-pane -t "server" "tee -a '/home/csgoserverp/test.txt