NpgsqlConnection hangs for hours on opening connection

问题

I was able to successfully connect using Npgsql nuget package, until one day the program started hanging for hours on executing conn.Open() without returning. I can successfully connect with Aginity client with same parameters. I tried Firewall On and Off. I tried Antivirus On and Off. I tried Fiddler On and Off.

Some things to Note: I need to be on VPN to connect to that host. It just hangs for hours, when conn.Open() is executed. When I am not on VPN, it times out immediately. We can't see actual incoming connections to the host, just queries. But the code doesn't get to the query part, it hangs on opening connection.

using (var conn = new NpgsqlConnection(connString))
            {
                conn.Open();                                
                using (var cmd = new NpgsqlCommand(command, conn))
                ...

回答1:

It looks that in Aginity client, SSL Mode is set to Require and default value in Npgsql for SSL Mode is Disable, according to docs(https://www.npgsql.org/doc/connection-string-parameters.html). But when I am setting SSL Mode parameter of Require in connection string, I get the following exception: Npgsql.PostgresException: 42704: unrecognized configuration parameter "ssl_renegotiation_limit"

While looking online for possible solution, I found this thread created by Npgsql nuget package owner. And from what it looks like, it may be an issue, that's in a feature request state: https://forums.aws.amazon.com/thread.jspa?threadID=229990

来源：https://stackoverflow.com/questions/53218192/npgsqlconnection-hangs-for-hours-on-opening-connection