A tcp server redirect clients to another tcp server written in c and libev.

基于 c 和 libev 编写的 TCP 端口转发服务器。

tcpredirection is a tcp server that accept some ports connections and make some connections to remote server, transmit data between clients and remote server.

tcpredirection 是一个 TCP 服务端程序，它接受本地端口的入站连接，同时创建到远程服务器端口的连接，并交换客户端和远程服务器间的数据通信。

tcpredirection use two text files in current working direction, ip.txt for in-comming clients ip whitelist filter, tr.txt for redirection rules.

Every line in ip.txt should contain a ip address that match client's peer ip which be allowed in-comming.

Every line in tr.txt should using format 'port remote_ip remote_port' (for example '8000 192.168.0.111 8000'), port is the port will listen on, remote_ip and remote_port is the target host and port which will redirect to.

tcpredirction 使用当前工作目录的两个文本文件：ip.txt 文件保存了连接本机的客户端IP的过滤列表；tr.txt 保存了端口转发规则。

ip.txt 每行文件应该包含一个允许连接本机的客户端IP地址。

tr.txt 每行的格式应该如 "本地端口 远程主机地址 远程主机端口" (例如 '8000 192.168.0.111 8000')，本地端口是程序将监听的端口，远程在主机地址和远程主机端口则是将转发到的目的地。

1. tcpredirection will cache size limited client's in-comming data before remote connection complete, the limit size is 1KB (you can modify it in source code). This is useful for some protocol like ntrip.

tcpredirection 会缓存一定长度的客户端发送来的数据，直到转发的远程连接完成再进行写入，缓存限制大小是 1KB，可以在代码中进行修改。这个特性适合类似 ntrip 协议的某些协议。

2. tr.txt 's remote address can use domains, but it will blocking the program when resolving. Use ip address make better performance.

tr.txt 中的远程地址可以使用域名，但是需要注意的是在解析域名的时候会阻塞程序。使用 IP 地址可以获得更好的性能。