Port 8088 HTTP alt / Hadoop · TCP

What runs on port 8088

Hadoop YARN ResourceManager web UI, Splunk HTTP Event Collector (HEC), Asterisk ARI/HTTP, and another http-alt in general. On a Hadoop cluster it exposes job details and, in old versions, remote command execution via the REST API, so internal only.

Software that uses it: Hadoop YARN ResourceManager · Splunk HEC · Asterisk HTTP (ARI, WebRTC)

Should port 8088 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.

• Splunk HEC should be fronted by TLS and uses token authentication; YARN needs Kerberos to be safe.

Check port 8088

# on the host: is anything listening, and which process?
ss -ltnp 'sport = :8088'
sudo lsof -i :8088

# from another machine: is it reachable?
nc -zv host 8088
nmap -p 8088 host
curl -v telnet://host:8088      # 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 8088

# ufw (Ubuntu/Debian)
sudo ufw allow from 10.0.0.0/8 to any port 8088 proto tcp
sudo ufw deny 8088/tcp

# nftables
nft add rule inet filter input ip saddr 10.0.0.0/8 tcp dport 8088 accept
nft add rule inet filter input tcp dport 8088 drop

# iptables (legacy)
iptables -A INPUT -p tcp --dport 8088 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8088 -j DROP

# firewalld
sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=10.0.0.0/8 port port=8088 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 8088" with no source is just "open".

Putting it behind nginx

server {
    listen 443 ssl;
    server_name app.example.com;
    location / {
        proxy_pass http://127.0.0.1:8088;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto https;
    }
}

Then make the application listen on 127.0.0.1:8088 only. Test which location block a request hits with the nginx location tester.

Related ports

• 8080 HTTP alt — Tomcat, proxies, dev servers

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