Package: mpg123 Version: 1.23.8-1+b1 It appears that mpg123(1) fails to notice the :PORT suffix when parsing an http_proxy value that contains an IPv6 address.
Consider, e. g.: $ http_proxy=http://\[::1\]:8080/ \ strace -o "$(mktemp -- /tmp/strace.XXXXXXXX)" -- \ mpg123 --test -- http://stream.chipbit.net:8000/autodj.m3u High Performance MPEG 1.0/2.0/2.5 Audio Player for Layers 1, 2 and 3 version 1.23.8; written and copyright by Michael Hipp and others free software (LGPL) without any warranty but with best wishes HTTP request failed: 404 Not Found main: [src/mpg123.c:709] error: Access to http resource http://stream.chipbit.net:8000/autodj.m3u failed. $ The strace(1) output reveals that mpg123(1) tries to connect to the default HTTP port (80), not the one specified (8080): connect(3, {sa_family=AF_INET6, sin6_port=htons(80), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=htonl(0), sin6_scope_id=0}, 28) = 0 Also to note is that using an (IPv6-only) name (as shown below) in place of the IPv6 address does not cause the issue. $ http_proxy=http://ip6-localhost:8080/ \ mpg123 --test -- http://stream.chipbit.net:8000/autodj.m3u -- FSF associate member #7257 58F8 0F47 53F5 2EB2 F6A5 8916 3013 B6A0 230E 334A