Port 6033 ProxySQL · TCP

What runs on port 6033

ProxySQL's client-facing MySQL port (the admin interface is on 6032). Applications connect here instead of to MySQL directly and get connection pooling, read/write splitting and query rules. Same exposure rules as 3306.

Software that uses it: ProxySQL

Should port 6033 be open?

Private network or VPN only. Nothing good comes from this port being reachable from the internet. Keep it on an internal network, reach it over a VPN or an SSH tunnel, and firewall it from everything that does not need it.

• Yes, 6033 is 3306 backwards; the admin port 6032 is 2306 backwards too.

Check port 6033

# on the host: is anything listening, and which process?
ss -ltnp 'sport = :6033'
sudo lsof -i :6033

# from another machine: is it reachable?
nc -zv host 6033
nmap -p 6033 host
curl -v telnet://host:6033      # raw TCP connect test, Ctrl-C to leave

A port that answers from the internet when it should not is the finding; nmap from a machine outside your network (or a VPS) is the honest test, because scans from inside the LAN pass the firewall you are trying to verify.

Allow or block port 6033

# ufw (Ubuntu/Debian)
sudo ufw allow from 10.0.0.0/8 to any port 6033 proto tcp
sudo ufw deny 6033/tcp

# nftables
nft add rule inet filter input ip saddr 10.0.0.0/8 tcp dport 6033 accept
nft add rule inet filter input tcp dport 6033 drop

# iptables (legacy)
iptables -A INPUT -p tcp --dport 6033 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 6033 -j DROP

# firewalld
sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=10.0.0.0/8 port port=6033 protocol=tcp accept'

Replace 10.0.0.0/8 with the networks that need access. Allowing by source address is the rule that matters; "allow 6033" with no source is just "open".

Related ports

• 3306 MySQL / MariaDB

Part of the port number reference. Ports are 16-bit numbers; see also the subnet calculator and the packet decoder, which shows ports inside TCP and UDP headers.

Questions