IP spoofing is attractive to amplify network attacks and to provide anonymity. Many approaches have to prevent IP spoofing attacks; however, they do not address a significant deployment issue: filtering inefficiency caused by lack of incentives for early adopters. Practically, no mechanism has been widely deployed and none successfully blocks IP spoofing attacks. We propose a universal anti-spoofing (UAS) mechanism that incorporates existing mechanisms to thwart IP spoofing attacks. In the proposed mechanism, intermediate routers utilize any existing anti-spoofing mechanism that ascertains whether a packet is spoofed or not, and inscribes this information in the packet header. The edge routers at a victim network can estimate the forgery of a packet based on the information sent by the upstream routers. The results of experiments conducted with Internet topologies indicate that UAS reduces false alarms up to 84.5% compared to cases where each mechanism operates separately. Our evaluation shows that incorporating multiple anti-spoofing mechanisms reduces false alarms significantly.