MySQL remote connection - 2 network cards

Question

This is not a duplicate - something is different here.

OS: Ubuntu 18.10 - 4.18.0-25-generic

Mysql Version': mysql Ver 14.14 Distrib 5.7.26, for Linux (x86_64) using EditLine wrapper

I am unable to connect to a "remote" mysql instance on my local network. I have set it up as described in numerous posts, only difference is I have 2 nics in my server.

So far I have:

Set "bind-address = 0.0.0.0" in /etc/mysql/mysql.conf.d/mysqld.cnf

Opened up TCP 3306 on the firewall

I can:

telnet localhost 3306 - and I get some mysql info and some form of prompt

netstat -nltp shows that mysql is bound to 0.0.0.0:3306

Use mysql normally from localhost, ie, mysql -u user -p lets me get into the db as $user just fine.

I can't:

(from remote) mysql -u user -p -h 192.168.0.51 (or on .52, same machine)

Result:

ERROR 2003 (HY000): Can't connect to MySQL server on '192.168.0.51' (113)

(from remote) telnet 192.168.0.51 3306

Result:

Trying 192.168.0.51... telnet: Unable to connect to remote host: No route to host

Even if i set the bind address to one of the NICs IP addresses, I am still unable to remotely connect to it.

"nmap -Pn 192.168.0.51 -p3306" returns that the port is filtered. Other ports can be opened and closed, and provided there is a listening service, I can connect via telnet to that service.

So - I have mysql set up correctly, I think, and I have the firewall set up correctly too.

/etc/mysql/mysql.conf.d/mysqld.cnf is as follows (minus comments):

root@mycloud:~# cat /etc/mysql/mysql.conf.d/mysqld.cnf | egrep -v "^\s*(#|$)"
[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0
[mysqld]
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
bind-address        = 0.0.0.0
key_buffer_size     = 16M
max_allowed_packet  = 16M
thread_stack        = 192K
thread_cache_size       = 8
myisam-recover-options  = BACKUP
query_cache_limit   = 1M
query_cache_size        = 16M
log_error = /var/log/mysql/error.log
expire_logs_days    = 10
max_binlog_size   = 100M
root@mycloud:~# 

My ufw status output:

root@mycloud:~# ufw status
Status: active

To                         Action      From
--                         ------      ----
22/tcp                     ALLOW       Anywhere                  
22                         ALLOW       Anywhere                  
3306/tcp                   ALLOW       Anywhere                  
3309/tcp                   ALLOW       Anywhere                  
3309                       ALLOW       Anywhere                  
3306                       ALLOW       Anywhere                  
8989/tcp                   ALLOW       Anywhere                  
22/tcp (v6)                ALLOW       Anywhere (v6)             
22 (v6)                    ALLOW       Anywhere (v6)             
3306/tcp (v6)              ALLOW       Anywhere (v6)             
3309/tcp (v6)              ALLOW       Anywhere (v6)             
3309 (v6)                  ALLOW       Anywhere (v6)             
3306 (v6)                  ALLOW       Anywhere (v6)             
8989/tcp (v6)              ALLOW       Anywhere (v6)             

root@mycloud:~# 

And my netstat output showing that its listening correctly:

root@mycloud:~# netstat -nltp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN      21396/mysqld        
tcp        0      0 0.0.0.0:139             0.0.0.0:*               LISTEN      2017/smbd           
tcp        0      0 0.0.0.0:8080            0.0.0.0:*               LISTEN      1189/utserver       
tcp        0      0 127.0.0.1:10000         0.0.0.0:*               LISTEN      1189/utserver       
tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      1448/systemd-resolv 
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1910/sshd           
tcp        0      0 0.0.0.0:445             0.0.0.0:*               LISTEN      2017/smbd           
tcp        0      0 0.0.0.0:8989            0.0.0.0:*               LISTEN      1138/mono           
tcp        0      0 0.0.0.0:6881            0.0.0.0:*               LISTEN      1189/utserver       
tcp        0      0 0.0.0.0:10050           0.0.0.0:*               LISTEN      1657/zabbix_agentd  
tcp        0      0 127.0.0.1:39621         0.0.0.0:*               LISTEN      1637/containerd     
tcp        0      0 0.0.0.0:7878            0.0.0.0:*               LISTEN      1227/mono           
tcp6       0      0 :::139                  :::*                    LISTEN      2017/smbd           
tcp6       0      0 :::80                   :::*                    LISTEN      2373/apache2        
tcp6       0      0 :::8080                 :::*                    LISTEN      1189/utserver       
tcp6       0      0 :::21                   :::*                    LISTEN      1638/vsftpd         
tcp6       0      0 :::22                   :::*                    LISTEN      1910/sshd           
tcp6       0      0 :::445                  :::*                    LISTEN      2017/smbd           
tcp6       0      0 :::6881                 :::*                    LISTEN      1189/utserver       
tcp6       0      0 :::10050                :::*                    LISTEN      1657/zabbix_agentd  
root@mycloud:~# 

Why cant I connect? I'm happy to close this off if someone can spot an easy error - I cant.

Internet hugs to anyone who can assist.