Well-known · Cross-platform

7 Echo Protocol

TCP Yes
UDP Yes
SCTP —
DCCP —

What it is

Echoes back any data it receives.

When / why

Legacy connectivity testing. Usually disabled on modern hosts to avoid amplification abuse.

Protocol status detail

TransportStatusMeaning
TCP Yes Assigned by IANA and standardized, specified, or widely used on this port.
UDP Yes Assigned by IANA and standardized, specified, or widely used on this port.
SCTP — Not applicable for this transport.
DCCP — Not applicable for this transport.
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Port range

Well-known (0–1023). System port for a core service. On Unix-like systems, binding it requires superuser privileges.

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Firewall rules for port 7

Copy-ready inbound rules for the active transports. Replace every <source> placeholder with the specific host, subnet, or CIDR that should reach this port.

⚠ UDP amplification risk — restrict or disable on internet-facing interfaces.

ufw

sudo ufw allow proto tcp from <source> to any port 7

Allow TCP 7 (Echo Protocol). Replace <source> with the network/host that should reach it.

sudo ufw allow proto udp from <source> to any port 7

Allow UDP 7 (Echo Protocol). Replace <source> with the network/host that should reach it.

firewalld

sudo firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<source>" port port="7" protocol="tcp" accept'

Allow TCP 7 (Echo Protocol) from <source>. Run 'firewall-cmd --reload' afterwards.

sudo firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<source>" port port="7" protocol="udp" accept'

Allow UDP 7 (Echo Protocol) from <source>. Run 'firewall-cmd --reload' afterwards.

nftables

nft add rule inet filter input ip saddr <source> tcp dport 7 accept

Allow TCP 7 (Echo Protocol). Assumes table 'inet filter' with an 'input' chain.

nft add rule inet filter input ip saddr <source> udp dport 7 accept

Allow UDP 7 (Echo Protocol). Assumes table 'inet filter' with an 'input' chain.

iptables

sudo iptables -A INPUT -p tcp -s <source> --dport 7 -j ACCEPT

Allow TCP 7 (Echo Protocol). Persist with iptables-save/netfilter-persistent.

sudo iptables -A INPUT -p udp -s <source> --dport 7 -j ACCEPT

Allow UDP 7 (Echo Protocol). Persist with iptables-save/netfilter-persistent.

Azure NSG

az network nsg rule create -g <resource-group> --nsg-name <nsg> -n Allow-echoprotocol-7 --priority 1000 --access Allow --direction Inbound --protocol "*" --source-address-prefixes <source> --destination-port-ranges 7

Inbound rule for 7 (Echo Protocol). Set <source> to a CIDR; lower priority number = higher precedence.

AWS Security Group

aws ec2 authorize-security-group-ingress --group-id <sg-id> --ip-permissions IpProtocol=tcp,FromPort=7,ToPort=7,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound TCP 7 (Echo Protocol). Replace <source-cidr> (e.g. 10.0.0.0/16).

aws ec2 authorize-security-group-ingress --group-id <sg-id> --ip-permissions IpProtocol=udp,FromPort=7,ToPort=7,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound UDP 7 (Echo Protocol). Replace <source-cidr> (e.g. 10.0.0.0/16).

GCP firewall

gcloud compute firewall-rules create allow-echoprotocol-7 --direction=INGRESS --action=ALLOW --rules=tcp:7,udp:7 --source-ranges=<source-cidr> --network=<network>

Ingress rule for 7 (Echo Protocol). Scope with --source-ranges and optionally --target-tags.

Windows netsh

netsh advfirewall firewall add rule name="Allow Echo Protocol 7/TCP" dir=in action=allow protocol=TCP localport=7 remoteip=<source>

Inbound TCP 7 (Echo Protocol). Set remoteip to a host/subnet; 'any' is discouraged.

netsh advfirewall firewall add rule name="Allow Echo Protocol 7/UDP" dir=in action=allow protocol=UDP localport=7 remoteip=<source>

Inbound UDP 7 (Echo Protocol). Set remoteip to a host/subnet; 'any' is discouraged.

Windows PowerShell

New-NetFirewallRule -DisplayName "Allow Echo Protocol 7/TCP" -Direction Inbound -Action Allow -Protocol TCP -LocalPort 7 -RemoteAddress <source>

Inbound TCP 7 (Echo Protocol). Replace <source> with a host or subnet.

New-NetFirewallRule -DisplayName "Allow Echo Protocol 7/UDP" -Direction Inbound -Action Allow -Protocol UDP -LocalPort 7 -RemoteAddress <source>

Inbound UDP 7 (Echo Protocol). Replace <source> with a host or subnet.

Rules are generated only for transports marked active for this port. They default to an inbound allow with an explicit source placeholder — never any. Review direction, scope, and rule precedence before applying in production.