buf_append(reqbuf, "X-CSTP-Version: 1\r\n");
buf_append(reqbuf, "X-CSTP-Hostname: %s\r\n", vpninfo->localname);
+ /* Some servers only allow connection if they see a shibboleth in the form of a standard copyright blurb: */
+ buf_append(reqbuf, "X-CSTP-Protocol: Copyright (c) %d %s\r\n",
+ 2004, "Cisco Systems, Inc.");
+
#ifdef HAVE_HPKE_SUPPORT
if (!vpninfo->no_external_auth && vpninfo->strap_pubkey)
append_connect_strap_headers(vpninfo, reqbuf, strap_rekey);