Question : How to  sniff packets from router

What is the best way to look at real time traffic on you r router?? Can this be done with Linux/Unix? IS there some kind of command line tool to do this.

Thanks

Answer : How to  sniff packets from router

"Also how would you re-route traffic say for ftp"

You don't mention what kind of routers you have but if they are Cisco you may be able to use Policy Based Routing to do this. (other routers support this as well) It still depends on your topology.

Basically Policy Based Routing uses access lists and route-maps to make routing decisions. If you use Extended access lists, the decision could be based on TCP ports, along with Source and Destination. It doesn't control the destination of a packet, but can control the path it takes.  

Here's a few links if you want to read more.

http://www.21stcenturyarticles.com/Article/Cisco-CCNP---BSCI-Exam-Tutorial---Introduction-To-Policy-Routing/580
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt2/1cfindep.htm#wp1001398
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fqos_c/fqcprt1/qcfpbr.htm

 
Cheers,

Gary