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// File transfer & sharing

Port 2773: RBackup Remote Backup

Port 2773 is assigned by IANA to rbakcup1 (RBackup Remote Backup).

2773

How rbakcup1 works

File transfer & sharing
client:27731/32/33/3rbakcup1 client:27731/32/33/3rbakcup1

Files are sent over port 2773 in pieces and reassembled on the other side.

Transport
TCP · 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
File transfer & sharing
01 Security

Is port 2773 dangerous?

We have no specific security note for port 2773. Its risk depends on the program actually listening on it. General advice for file transfer & sharing services:

  • Prefer encrypted protocols (SFTP, FTPS, SMB 3 with encryption).
  • Disable anonymous access and restrict shares or exports to known hosts.
  • Never publish file sharing protocols to the Internet.
02 Registry

IANA registry entries for port 2773

ServicePortTransportDescriptionReferenceUpdated
rbakcup1 2773 TCP, UDP RBackup Remote Backup - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2773, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2773'      # process listening on 2773
sudo lsof -nP -i :2773

macOS

sudo lsof -nP -i :2773

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2773 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2773
netstat -ano | findstr :2773

From another machine

nmap -p 2773 -sV <host>
sudo nmap -sU -p 2773 <host>
nc -zv <host> 2773

Block it in the firewall

sudo ufw deny 2773/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2773" -Direction Inbound -LocalPort 2773 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2773 used for?

Port 2773 is assigned by IANA to rbakcup1 (RBackup Remote Backup).

Is port 2773 TCP or UDP?

Port 2773 is registered for TCP and UDP.

Is it safe to open port 2773?

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. Prefer encrypted protocols (SFTP, FTPS, SMB 3 with encryption).

How do I check if port 2773 is open?

On Linux run "ss -ltnup 'sport = :2773'", on macOS "lsof -nP -i :2773", and on Windows "netstat -ano | findstr :2773" to see the local process. From another machine, "nmap -p 2773 <host>" shows whether it is reachable.

05 Related
:445 SMB tcp · udp · critical risk :21 FTP tcp · udp · sctp · high risk :139 NetBIOS Session tcp · udp · high risk :69 TFTP udp · tcp · high risk :2049 NFS tcp · udp · sctp · high risk :873 rsync tcp · udp · high risk :20 File Transfer [Default Data] tcp · udp · sctp :115 Simple File Transfer Protocol tcp · udp

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