I am behind a proxy in a corporate environment:
$ printenv | grep proxy
http_proxy=http://aproxy.corproot.net:8080/
https_proxy=http://aproxy.corproot.net:8080/
and trying to access the following 2 URLs from the terminal using wget or curl (there resources are not accessible from the Internet):
https://artifactory.swisscom.com/api/npm/npm-remote/npm/-/npm-5.1.0.tgzhttps://artifactory.swisscom.com/api/npm/npm-remote/npm/-/npm-5.10.0.tgz
The first one returns 503 Service Unavailable while the 2nd returns 200 and the file is downloaded.
When accessed from web browsers on the same computer (with the same HTTP/S proxy set), both URLs are downloading the file (in any browser: Chrome, Firefox, Safari). Also my colleagues with the same OS version (macOS Catalina 10.15.6) and with the same proxy settings like me, can download (wget or curl) both files from the terminal.
So it cannot be a server error on the side of Artifactory or a proxy error. There must be a configuration on my side that breaks the access to the npm-5.1.0.tgz URL.
What could be the issue on my system or how can I troubleshoot it such that I determine what the issue can be?
The result I get when I access the npm-5.1.0.tgz URL in the terminal is:
<HTML><HEAD>
<TITLE>ICAP Error</TITLE>
</HEAD>
<BODY>
<FONT face="Helvetica">
<big><strong></strong></big><BR>
</FONT>
<blockquote>
<TABLE border=0 cellPadding=1 width="80%">
<TR><TD>
<FONT face="Helvetica">
<big>ICAP Error (icap_error)</big>
<BR>
<BR>
</FONT>
</TD></TR>
<TR><TD>
<FONT face="Helvetica">
An error occurred while performing an ICAP operation: File decompression/decode error; File: npm-5.1.0.tgz; Sub File: ; Vendor: Sophos, Plc.; Engine version: 3.79.0; Pattern version: 5.77.53271598.0; Pattern date: 2020/09/03 08:28:38
</FONT>
</TD></TR>
<TR><TD>
<FONT face="Helvetica">
There could be a network problem, the ICAP service may be misconfigured, or the ICAP server may have reported an error.
</FONT>
</TD></TR>
<TR><TD>
<BR>
<FONT face="Helvetica">
Transaction ID: c096ba71d6c6f520-00000001bb135417-000000005f50eafc
</FONT>
</TD></TR>
<TR><TD>
<FONT face="Helvetica" SIZE=2>
<BR>
For assistance, contact your network support team.<br><br>Your request was categorized by Blue Coat Web Filter as 'Technology/Internet'. <br>If you wish to question or dispute this result, please click <a href="http://sitereview.bluecoat.com/sitereview.jsp?referrer=136&url=https://artifactory.swisscom.com/api/npm/npm-remote/npm/-/npm-5.1.0.tgz">here</a>.
</FONT>
</TD></TR>
</TABLE>
</blockquote>
</FONT>
</BODY></HTML>
The difference between the successful URL (npm-5.10.0.tzg) and the failing URL (npm-5.1.0.tgz) is also visible in Wireshark (a network inspector tool):
Successful URL (TCP FIN):
Failing URL (Encrypted Alert and TCP RST:
