Port 70 Gopher · TCP

What runs on port 70

Gopher: the menu-based document protocol that competed with the early web. A small community still runs Gopher servers, and modern browsers no longer speak it, but it is worth knowing when it appears in a scan or a URL.

Software that uses it: pygopherd · gophernicus · Lynx (client)

Should port 70 be open?

Disable it. This is a legacy or insecure protocol. The recommendation is not to firewall it but to turn the service off and use the modern replacement.

• Gemini (port 1965) is the modern spiritual successor if you are curious.

Check port 70

# on the host: is anything listening, and which process?
ss -ltnp 'sport = :70'
sudo lsof -i :70

# from another machine: is it reachable?
nc -zv host 70
nmap -p 70 host
curl -v telnet://host:70      # 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 70

# ufw (Ubuntu/Debian)
sudo ufw allow from 10.0.0.0/8 to any port 70 proto tcp
sudo ufw deny 70/tcp

# nftables
nft add rule inet filter input ip saddr 10.0.0.0/8 tcp dport 70 accept
nft add rule inet filter input tcp dport 70 drop

# iptables (legacy)
iptables -A INPUT -p tcp --dport 70 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 70 -j DROP

# firewalld
sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=10.0.0.0/8 port port=70 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 70" with no source is just "open".

Related ports

• 80 HTTP — Web, unencrypted
• 79 finger

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