Is there a linux command/tool that will provide end-to-end bandwidth information between local and external host?

CentOS 5.x

At times, I've wanted to know what general bandwidth constraints exist between my servers and an external server that I don't have control over. Is there a linux command/tool that could provide this information?

Historically I've used tools like wget and scp to get a rough estimate from transfer speed summaries (in situations where the remote server is providing publicly accessible files). Is there anything else? I would assume not since there would likely be security repercussions in freely disclosing that information.

Check out iperf (http://iperf.sf.net). It has a client/server architecture.

The basic idea is that you have a server on one side of your network path, and one or multiple clients trying to connect to it. It has multiple options like TCP or UDP, single flow versus several flows, daemon mode, etc. I have been using it for testing bufferbloat, sustained bandwidth, MTU size, network loss and several other things.

It also has support for Jumbo Frames and IPv6.

This assumes that you have root access on both sides, of course. If that's not the case, could you give us more information about your setup?

You should be able to get packages for CentOS 5 from http://pkgs.org/centos-5-rhel-5/epel-x86_64/iperf-2.0.5-1.el5.x86_64.rpm.html for example, I think they come from Fedora.