This paper presents Telemetron, the first active bandwidth measurement tool that can estimate the path capacity between two remote hosts, from an off-path Measuring Machine (MM). It is possible to induce traffic flow between off-path remote hosts—sending request packets to one host, with a spoofed source IP, will cause the first host to send reply packets to the other. The challenge for MM is to measure the rate at which these packets arrive at the second machine. Our key observation is that if the second machine has a global IP-ID counter, the arrival of packets can be monitored remotely, using probes from MM. By observing the rate of increment in the global IP-ID counter, MM estimates the path capacity between remote hosts. Telemetron shows high accuracy; on average, the path capacity reported is 92.5% of the theoretical limit.