Mac OS X slow connections - mdns 4-5 seconds - bonjour slow

Question

I'm finally at my wits end. I've been Googling this issue for a week now. I've tried troubleshooting my Mac (10.12 Sierra) and my domain controllers (Windows Server 2016) and I am no closer to solving my issue.

My issue is that when using PHP's ldap_connect() function, it takes about 5 seconds before I get a response. Things just sort of hang for 5 seconds then I get a successful connection. The exact command to replicate this (assuming my DC has an IP address of 192.168.2.5):

$ldap = ldap_connect('ldap://192.168.2.5:389');

I'm not using SSL or TLS. It's just a simple plaintext connection to a DC with its firewall completely turned off. I ended up installing Wireshark on my DC to get more information with what is going on and I noticed this:

1 | 327 | 192.168.2.108 | 224.0.0.251 | MDNS | 83 | Standard query 0x0000 A Ryans-MacBook-Pro.local, "QU" question

2 | 328 | 192.168.2.108 | 224.0.0.251 | MDNS | 83 | Standard query 0x0000 A Ryans-MacBook-Pro.local, "QM" question

3 | 331 | 192.168.2.108 | 224.0.0.251 | MDNS | 83 | Standard query 0x0000 A Ryans-MacBook-Pro.local, "QM" question

4 | 332 | 192.168.2.108 | 192.168.2.5 | TCP | 78 | 49860 > 389 [SYN] Seq=0 Win=65535 Len=0 MSS=1460 WS=32 TSval=371626102 TSecr=0 SACK_PERM=1

5 | 332 | 192.168.2.5 | 192.168.2.108 | TCP | 74 | 389 > 49860 [SYN, ACK] Seq=0 Ack=1 Win=8192 Len=0 MSS=1460 WS=256 SACK_PERM=1 TSval=2494847497 TSecr=371626102

6 | 332 | 192.168.2.108 | 192.168.2.5 | TCP | 66 | 49860 > 389 [ACK] Seq=1 Ack=1 Win=131744 Len=0 TSval=371626102 TSecr=2494847497

7 | 332 | 192.168.2.108 | 192.168.2.5 | LDAP | 96 | bindRequest(1) "ldap" simple

8 | 332 | 192.168.2.5 | 192.168.2.108 | LDAP | 88 | bindResponse(1) success

As you can see, when I initiate the ldap_connect() function, I immediate see the first packet at 327 seconds (since running Wireshark). I see 3 mdns packets for a total of 5 seconds. Then on the fourth, fifth and sixth packets I see the TCP three-way handshake and then it continues to give me a successful ldap connection. Therefore the 5 second delay I'm seeing is all mdns packets or Apple's Bonjour? At this point, I have no idea how to fix this.

Disclaimer: I am using Laravel Valet which uses dnsmasq. I have no idea if this is causing my issue or not. I have not uninstalled this software yet to find out.

edit: I've ruled out Laravel Valet. I completely uninstalled it and it's still an issue. I've also ruled out Laravel. I'm running this script and the issue still exists:

<?php

$start = microtime(true);

$ldap = ldap_connect('ldap://192.168.2.5:389');

$end = microtime(true);

echo $end - $start;

edit2: Ok I've gotten further with solving this. I installed Wireshark on my Mac and noticed the below as well.

Then I ran this command: ➜ ~ scutil --dns DNS configuration

resolver #1
  search domain[0] : corp.[redacted].com
  nameserver[0] : 192.168.2.4
  nameserver[1] : 192.168.2.5
  if_index : 7 (en3)
  flags    : Request A records
  reach    : Reachable, Directly Reachable Address

resolver #2
  domain   : local
  options  : mdns
  timeout  : 5
  flags    : Request A records
  reach    : Not Reachable
  order    : 300000

It's my hostname! My hostname is causing a 5 second delay trying to resolve it using multicast DNS. Why? .local is a reserved domain so why would Apple append it to my hostname?

As you can see, it automatically appends .local.

Anyway, I've resolved my issue by adding 127.0.0.1 Ryans-MacBook-Pro.local to my /etc/hosts file. For some reason it wasn't in there.

My ldap_connect() is now instant like it should be!

I also get that 5 secs when resolving from `/etc/hosts` ... seems like an mDNSresponder issue . — YvesLeBorg, Jun 26 '17 at 13:17
Since I'm using the ip address of the server and not the hostname or FQDN, I have no idea why it would even try to resolve out of /etc/hosts or even DNS for that matter? — Ryan Mortier, Jun 26 '17 at 13:20
after investigating, it seems that i get the 5 seconds when coming from a php process (cli and via sapi) ... and not in shell. More investigation in progress. — YvesLeBorg, Jun 26 '17 at 13:26
this solves it for me , but not certain how it relates to ldap : `curl_setopt($ch, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);` , apparently some weird issue with ipv6. If you have access to php.ini, try to add this via `curl` options. — YvesLeBorg, Jun 26 '17 at 13:38
I don't see any options like that for `ldap_connect()` http://php.net/manual/en/function.ldap-set-option.php — Ryan Mortier, Jun 26 '17 at 13:42
i was suggesting `php.ini` , default curl options (possibly in conf.d/ext-curl.ini on a mac., because under the hood php's `ldap_connect` could rely on php's `curl`. — YvesLeBorg, Jun 26 '17 at 13:44
See my edit2. I seem to have fixed this. Can you tell me what your `/etc/hosts` file looks like? — Ryan Mortier, Jun 26 '17 at 16:20
the most interesting part is that ldap_connect does *not* connect to the server. Internaly it calls ldap_initialize which creates an LDAP resource but does not open a network connection. The connection will be established as soon as a network connection is necessary (usually on ldap_bind) - That does *not* refer to f.e. DNS queries or stuff like that... — heiglandreas, Jun 27 '17 at 14:37

score 5 · Accepted Answer · answered Jun 26 '17 at 16:36

5

Make sure your hostname is in the /etc/hosts file like this:

127.0.0.1 localhost Ryans-MacBook-Pro.local

Just replace my hostname with yours.

answered Jun 26 '17 at 16:36

Ryan Mortier

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Mac OS X slow connections - mdns 4-5 seconds - bonjour slow

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