make proton client just works

[chenziliang]

Describe what enhancement you'd like to have

Right now, we may have to do proton client -h 127.0.0.1

[yokofly]

yes i use tcpdump verify the macOS default behaviour connect to ipv6

re@192 sub % sudo tcpdump -i any -n -vv -s 0 -c 100 -W 100 port 8463
tcpdump: data link type PKTAP
tcpdump: listening on any, link-type PKTAP (Apple DLT_PKTAP), snapshot length 524288 bytes
02:15:11.283676 IP6 (flowlabel 0xc0900, hlim 64, next-header TCP (6) payload length: 44) ::1.64694 > ::1.8463: Flags [S], cksum 0x0034 (incorrect -> 0x6c1e), seq 575930336, win 65535, options [mss 16324,nop,wscale 6,nop,nop,TS val 1139346665 ecr 0,sackOK,eol], length 0
02:15:11.283698 IP6 (flowlabel 0xc0900, hlim 64, next-header TCP (6) payload length: 44) ::1.64694 > ::1.8463: Flags [S], cksum 0x0034 (incorrect -> 0x6c1e), seq 575930336, win 65535, options [mss 16324,nop,wscale 6,nop,nop,TS val 1139346665 ecr 0,sackOK,eol], length 0
02:15:11.283731 IP6 (flowlabel 0xc0900, hlim 64, next-header TCP (6) payload length: 20) ::1.8463 > ::1.64694: Flags [R.], cksum 0x001c (incorrect -> 0x6fd4), seq 0, ack 575930337, win 0, length 0
02:15:11.283738 IP6 (flowlabel 0xc0900, hlim 64, next-header TCP (6) payload length: 20) ::1.8463 > ::1.64694: Flags [R.], cksum 0x001c (incorrect -> 0x6fd4), seq 0, ack 1, win 0, length 0