[TriLUG] TCP connections taking forever to form? [SOLVED]

[Brian via TriLUG]

Nevermind, folks.  It was an IPv6 issue.  I finally remembered that IPv6 
exists and that Spectrum in my area still does a rubbish job with it. 
So I did a couple things:

I tested curl -4 (forcing it to use IPv4) and presto, quick action.
I tested curl -6 (ensuring it used IPv6) and it took forever again.
I started up my Hurricane Electric IPv6 tunnel.
I tested curl -6 again and presto, quick action (a tad slower than -4 
but only by a second).

Sheesh!
-B

On 2/2/21 10:25 AM, Brian via TriLUG wrote:
> Hi Gang,
> 
> Something very strange is going on with my Centos 7.4 system, which acts 
> as my firewall and server of various things.  Mundane operations are 
> taking ages to complete and I think I have narrowed it down to a problem 
> establishing TCP connections.
> 
> I finally tracked down the slowdown by combing through a particular 
> shell-script I was using, so my examples below come from that (getssl).
> 
> I'm testing with this command:
> $ time curl --user-agent "getssl/2.33" -I 
> "https://acme-staging-v02.api.letsencrypt.org/"
> 
> Running that on my desktop machine (which is downstream of the server) 
> gives me a response right away:
> [...]
> real    0m0.375s
> user    0m0.016s
> sys    0m0.015s
> 
> 
> Running it on the server itself takes AGES:
> [...]
> real    2m7.775s
> user    0m0.076s
> sys    0m0.094s
> 
> Two MINUTES for a simple http request!  How can I figure out what in the 
> world is causing this?  I'm stumped...
> 
> TIA,
> -Brian