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// Network services

Port 6696: Babel Routing Protocol

Port 6696 is assigned by IANA to babel (Babel Routing Protocol).

6696

How babel works

Network services
client:6696babelresponse client:6696babelresponse

The client sends a request to port 6696 and the babel service answers.

Transport
UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned1 registered service
Range
Registered (1024-49151)
Category
Network services
01 Security

Is port 6696 dangerous?

We have no specific security note for port 6696. Its risk depends on the program actually listening on it. General advice for network services services:

  • Answer only the networks that need the service (no open resolvers, relays or reflectors).
  • UDP services can be abused for DDoS amplification: rate-limit or block them at the edge.
  • Disable legacy test services that have no use in production.
02 Registry

IANA registry entries for port 6696

ServicePortTransportDescriptionReferenceUpdated
babel 6696 UDP Babel Routing Protocol RFC 8966 2011-08-15
-6696-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 6696, and is it reachable?

Linux

sudo ss -ltnup 'sport = :6696'      # process listening on 6696
sudo lsof -nP -i :6696

macOS

sudo lsof -nP -i :6696

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 6696 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 6696
netstat -ano | findstr :6696

From another machine

nmap -p 6696 -sV <host>
sudo nmap -sU -p 6696 <host>
nc -zv <host> 6696

Block it in the firewall

sudo ufw deny 6696/udp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 6696" -Direction Inbound -LocalPort 6696 -Protocol UDP -Action Block  # Windows
04 FAQ
What is port 6696 used for?

Port 6696 is assigned by IANA to babel (Babel Routing Protocol).

Is port 6696 TCP or UDP?

Port 6696 is registered for UDP.

Is it safe to open port 6696?

It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Answer only the networks that need the service (no open resolvers, relays or reflectors).

How do I check if port 6696 is open?

On Linux run "ss -ltnup 'sport = :6696'", on macOS "lsof -nP -i :6696", and on Windows "netstat -ano | findstr :6696" to see the local process. From another machine, "nmap -p 6696 <host>" shows whether it is reachable.

05 Related
:53 DNS tcp · udp · moderate risk :135 MS RPC tcp · udp · high risk :123 NTP udp · tcp · moderate risk :67 DHCP server udp · tcp · moderate risk :111 rpcbind tcp · udp · high risk :9100 Raw printing (JetDirect) tcp · udp · high risk :631 IPP / CUPS tcp · udp · high risk :5353 mDNS udp · tcp · moderate risk

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