Well-known · Cross-platform

853 DNS over TLS / QUIC

TCP Yes
UDP Yes
SCTP —
DCCP —

What it is

Encrypted DNS: DoT over TCP/TLS (RFC 7858), DoQ over UDP/QUIC.

When / why

Privacy-preserving DNS to upstream resolvers.

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.
« 848 GDOI 860 iSCSI »

Port range

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

Browse all ports →

Firewall rules for port 853

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

ufw

sudo ufw allow proto tcp from <source> to any port 853

Allow TCP 853 (DNS over TLS / QUIC). Replace <source> with the network/host that should reach it.

sudo ufw allow proto udp from <source> to any port 853

Allow UDP 853 (DNS over TLS / QUIC). 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="853" protocol="tcp" accept'

Allow TCP 853 (DNS over TLS / QUIC) from <source>. Run 'firewall-cmd --reload' afterwards.

sudo firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<source>" port port="853" protocol="udp" accept'

Allow UDP 853 (DNS over TLS / QUIC) from <source>. Run 'firewall-cmd --reload' afterwards.

nftables

nft add rule inet filter input ip saddr <source> tcp dport 853 accept

Allow TCP 853 (DNS over TLS / QUIC). Assumes table 'inet filter' with an 'input' chain.

nft add rule inet filter input ip saddr <source> udp dport 853 accept

Allow UDP 853 (DNS over TLS / QUIC). Assumes table 'inet filter' with an 'input' chain.

iptables

sudo iptables -A INPUT -p tcp -s <source> --dport 853 -j ACCEPT

Allow TCP 853 (DNS over TLS / QUIC). Persist with iptables-save/netfilter-persistent.

sudo iptables -A INPUT -p udp -s <source> --dport 853 -j ACCEPT

Allow UDP 853 (DNS over TLS / QUIC). Persist with iptables-save/netfilter-persistent.

Azure NSG

az network nsg rule create -g <resource-group> --nsg-name <nsg> -n Allow-dnsovertlsquic-853 --priority 1000 --access Allow --direction Inbound --protocol "*" --source-address-prefixes <source> --destination-port-ranges 853

Inbound rule for 853 (DNS over TLS / QUIC). 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=853,ToPort=853,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound TCP 853 (DNS over TLS / QUIC). 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=853,ToPort=853,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound UDP 853 (DNS over TLS / QUIC). Replace <source-cidr> (e.g. 10.0.0.0/16).

GCP firewall

gcloud compute firewall-rules create allow-dnsovertlsquic-853 --direction=INGRESS --action=ALLOW --rules=tcp:853,udp:853 --source-ranges=<source-cidr> --network=<network>

Ingress rule for 853 (DNS over TLS / QUIC). Scope with --source-ranges and optionally --target-tags.

Windows netsh

netsh advfirewall firewall add rule name="Allow DNS over TLS / QUIC 853/TCP" dir=in action=allow protocol=TCP localport=853 remoteip=<source>

Inbound TCP 853 (DNS over TLS / QUIC). Set remoteip to a host/subnet; 'any' is discouraged.

netsh advfirewall firewall add rule name="Allow DNS over TLS / QUIC 853/UDP" dir=in action=allow protocol=UDP localport=853 remoteip=<source>

Inbound UDP 853 (DNS over TLS / QUIC). Set remoteip to a host/subnet; 'any' is discouraged.

Windows PowerShell

New-NetFirewallRule -DisplayName "Allow DNS over TLS / QUIC 853/TCP" -Direction Inbound -Action Allow -Protocol TCP -LocalPort 853 -RemoteAddress <source>

Inbound TCP 853 (DNS over TLS / QUIC). Replace <source> with a host or subnet.

New-NetFirewallRule -DisplayName "Allow DNS over TLS / QUIC 853/UDP" -Direction Inbound -Action Allow -Protocol UDP -LocalPort 853 -RemoteAddress <source>

Inbound UDP 853 (DNS over TLS / QUIC). 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.