Relay server blocked in China

[immartian]

One of my receivers in China reported he can't connect to relay server. I think the default relay server has been polluted on DNS resolution in China. So it won't work for travelers to this tightly-censored state. Any ideas?

His log:

ERROR: We had a problem connecting to the relay server:
(relay URL was ws://relay.magic-wormhole.io:4000/v1)
DNS lookup failed: no results for hostname lookup: relay.magic-wormhole.io.

[warner]

Wow. Hm, could they try replacing the server URL with one that only uses the (current) IP address?

wormhole --relay-url=ws://45.56.71.116:4000/v1 receive

That might not work because of the way that HTTP servers use the "Host:" header to figure out which site the client is trying to connect to, but since we don't tell the server its own hostname, I think it ought to work.

A second fallback might be to modify the receiving machine's /etc/hosts file to manually add the current address.

Please let me know if either of those works, or if we see evidence of the IP address being blocked too.

[warner]

Oh, if the transit relay is similarly DNS-blocked, they might also need to add --transit-helper=tcp:45.33.13.8:4001.

The transit helper is probably at a stable address for the next 6 months. I might be moving the relay server in a month or two, at which point the IP address would change, but I might be able to leave a port-forwarding from the old one in place. So if it works for a while, but then stops working in a few months, check to see if the DNS entry has changed and update the --relay-url= argument.

[reaperhulk]

I can't replicate this from Shanghai, but one of the obnoxious features of the great firewall is its inconsistency from location to location so this should not be taken as proof that there isn't blocking occurring somewhere in China.