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INTERCEPT(1) General Commands Manual INTERCEPT(1)

NAME

TCPCopy - online request replication tool, receiving server

SYNOPSIS

DESCRIPTION

TCPCopy is an online request replication tool using netlink and raw sockets. It can copy TCP flows from production environment to testing environment in real-time with very small impact on normal operation, so that it is a very handful tool for distributed stress testing, hot backup, online testing and benchmarking.

OPTIONS

Passed IP list through firewall, format: IP1,IP2,...
Bind IP address for listening.
Run as daemon.
Save logs in LOG_FILE
Set the TCP port number to listen on. Default value is 36524.
Save PID in PIDFILE , only use in conjunction with -d option.
Set the hash table size for intercept. Default value is 65536.
Set the router item timeout limit in seconds. Default value is 120.
Print help text and exit.
Print version info and exit.

NOTES

This program relies on the function of ip_queue module, you can check whether the module has been loaded by running: lsmod | grep ip_queue If it is not loaded, use modprobe ip_queue to load it.

After loading the ip_queue module, you need to set up iptables to queue requests for the port when are intercepting: iptables -I OUTPUT -p tcp --sport PORT -j QUEUE

When the presure is heavy, turning sysctl parameters may be necessary for better performance and lower packet (request) loss rate.

The status of ip_queue module can be found at /proc/net/ip_queue , if the number of Queue dropped is increasing, then it suggests net.ipv4.ip_queue_maxlen may need to be increased, and if Netlink dropped is increasing, then net.core.rmem_max and net.core.wmem_max may need to be increased.

It is also recommended to stop tcpcopy(1) before stopping intercept(1).

SEE ALSO

tcpcopy(1), /usr/share/doc/tcpcopy/README

AUTHOR

This manual page was written by Aron Xu <aron@debian.org> for the Debian GNU/Linux system (but may be used by others).