SSL session ID & IPS

Posted on by David Vassallo

Intermittent access issues to HTTPS sites… Issue : Randomly, the same HTTPS site would sometimes not respond. IE would show its very unhelpful “page cannot be displayed” while firefox displays the slightly more descriptive “peer recieved a valid certificate but access denied” Cause (in this case) : An upstream Fortigate IPS was dropping “unknown” SSL … Continue reading SSL session ID & IPS

TCP zero windows

Posted on by David Vassallo

Yet another reason downloads can fail… Issue : Large file is being downloaded (eg an ISO running above 500MBs). The file starts off downloading fine, but eventually stops downloading, leaving the file incomplete. Cause (in this case) : TCP zero windows caused the server to reset the connection Troubleshooting : In wireshark, run the following … Continue reading TCP zero windows