Registered · Cross-platform

11211 memcached

TCP Unofficial
UDP Unofficial
SCTP —
DCCP —

What it is

memcached distributed cache.

When / why

Caching. UDP/11211 is a severe DDoS amplifier — disable UDP and bind internally.

Protocol status detail

TransportStatusMeaning
TCP Unofficial Not assigned by IANA, but standardized, specified, or widely used on this port.
UDP Unofficial Not assigned by IANA, but standardized, specified, or widely used on this port.
SCTP — Not applicable for this transport.
DCCP — Not applicable for this transport.
« 10933 Octopus Tentacle 11214 memcached SSL »

Port range

Registered (1024–49151). Assigned by IANA on request; usable without elevated privileges on most systems.

Browse all ports →

Firewall rules for port 11211

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 11211

Allow TCP 11211 (memcached). Replace <source> with the network/host that should reach it.

sudo ufw allow proto udp from <source> to any port 11211

Allow UDP 11211 (memcached). 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="11211" protocol="tcp" accept'

Allow TCP 11211 (memcached) from <source>. Run 'firewall-cmd --reload' afterwards.

sudo firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<source>" port port="11211" protocol="udp" accept'

Allow UDP 11211 (memcached) from <source>. Run 'firewall-cmd --reload' afterwards.

nftables

nft add rule inet filter input ip saddr <source> tcp dport 11211 accept

Allow TCP 11211 (memcached). Assumes table 'inet filter' with an 'input' chain.

nft add rule inet filter input ip saddr <source> udp dport 11211 accept

Allow UDP 11211 (memcached). Assumes table 'inet filter' with an 'input' chain.

iptables

sudo iptables -A INPUT -p tcp -s <source> --dport 11211 -j ACCEPT

Allow TCP 11211 (memcached). Persist with iptables-save/netfilter-persistent.

sudo iptables -A INPUT -p udp -s <source> --dport 11211 -j ACCEPT

Allow UDP 11211 (memcached). Persist with iptables-save/netfilter-persistent.

Azure NSG

az network nsg rule create -g <resource-group> --nsg-name <nsg> -n Allow-memcached-11211 --priority 1000 --access Allow --direction Inbound --protocol "*" --source-address-prefixes <source> --destination-port-ranges 11211

Inbound rule for 11211 (memcached). 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=11211,ToPort=11211,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound TCP 11211 (memcached). 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=11211,ToPort=11211,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound UDP 11211 (memcached). Replace <source-cidr> (e.g. 10.0.0.0/16).

GCP firewall

gcloud compute firewall-rules create allow-memcached-11211 --direction=INGRESS --action=ALLOW --rules=tcp:11211,udp:11211 --source-ranges=<source-cidr> --network=<network>

Ingress rule for 11211 (memcached). Scope with --source-ranges and optionally --target-tags.

Windows netsh

netsh advfirewall firewall add rule name="Allow memcached 11211/TCP" dir=in action=allow protocol=TCP localport=11211 remoteip=<source>

Inbound TCP 11211 (memcached). Set remoteip to a host/subnet; 'any' is discouraged.

netsh advfirewall firewall add rule name="Allow memcached 11211/UDP" dir=in action=allow protocol=UDP localport=11211 remoteip=<source>

Inbound UDP 11211 (memcached). Set remoteip to a host/subnet; 'any' is discouraged.

Windows PowerShell

New-NetFirewallRule -DisplayName "Allow memcached 11211/TCP" -Direction Inbound -Action Allow -Protocol TCP -LocalPort 11211 -RemoteAddress <source>

Inbound TCP 11211 (memcached). Replace <source> with a host or subnet.

New-NetFirewallRule -DisplayName "Allow memcached 11211/UDP" -Direction Inbound -Action Allow -Protocol UDP -LocalPort 11211 -RemoteAddress <source>

Inbound UDP 11211 (memcached). 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.