Hello
Is this possible to let a canon camera (with CHDK) working together with cheap openwrt device to provide PTP/IP (PTP transfer the pictures over INTERNET)
It should theoretically be possible to write a PTP/IP to PTP/USB proxy, but I don't know if any exist. Some differences between the two make it not completely straightforward. *wrt routers also tend to have very limited resources, so it could be pretty tricky to get working even if a proxy already existed.
Canon cameras with Wifi use PTP/IP already.
PTP/IP is not something you'd normally want to expose directly on the internet.