diff -up openssl-1.1.1k/apps/s_socket.c.addr-ipv6 openssl-1.1.1k/apps/s_socket.c --- openssl-1.1.1k/apps/s_socket.c.addr-ipv6 2021-07-16 15:14:08.491986682 +0200 +++ openssl-1.1.1k/apps/s_socket.c 2021-07-16 15:23:21.271329197 +0200 @@ -214,6 +214,8 @@ int do_server(int *accept_sock, const ch const BIO_ADDRINFO *next; int sock_family, sock_type, sock_protocol, sock_port; const BIO_ADDR *sock_address; + int sock_family_fallback = AF_UNSPEC; + const BIO_ADDR *sock_address_fallback = NULL; int sock_options = BIO_SOCK_REUSEADDR; int ret = 0; @@ -244,6 +246,10 @@ int do_server(int *accept_sock, const ch && BIO_ADDRINFO_protocol(next) == sock_protocol) { if (sock_family == AF_INET && BIO_ADDRINFO_family(next) == AF_INET6) { + /* In case AF_INET6 is returned but not supported by the + * kernel, retry with the first detected address family */ + sock_family_fallback = sock_family; + sock_address_fallback = sock_address; sock_family = AF_INET6; sock_address = BIO_ADDRINFO_address(next); } else if (sock_family == AF_INET6 @@ -253,6 +259,10 @@ int do_server(int *accept_sock, const ch } asock = BIO_socket(sock_family, sock_type, sock_protocol, 0); + if (asock == INVALID_SOCKET && sock_family_fallback != AF_UNSPEC) { + asock = BIO_socket(sock_family_fallback, sock_type, sock_protocol, 0); + sock_address = sock_address_fallback; + } if (asock == INVALID_SOCKET || !BIO_listen(asock, sock_address, sock_options)) { BIO_ADDRINFO_free(res);