HTTPfy

Port 544 (kshell)

IANA assigns port 544 to kshell: krcmd.

Well-known (system) port, 0-1023 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
kshell TCP krcmd - -
kshell UDP krcmd - -

Check what is listening on port 544

Linux: is anything listening on TCP 544?
sudo ss -tlnp 'sport = :544'
Linux: UDP 544
sudo ss -ulnp 'sport = :544'
Linux / macOS: which process owns the port
sudo lsof -nP -i :544
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':544 '
Windows (Command Prompt)
netstat -ano | findstr :544
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 544 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 544
From Windows
Test-NetConnection HOST -Port 544
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 544

Block port 544 in the firewall

ufw
sudo ufw deny 544/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 544 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 544 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 544' -Direction Inbound -Protocol TCP -LocalPort 544 -Action Block
ufw
sudo ufw deny 544/udp
iptables
sudo iptables -A INPUT -p udp --dport 544 -j DROP
nftables
sudo nft add rule inet filter input udp dport 544 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 544' -Direction Inbound -Protocol UDP -LocalPort 544 -Action Block

Related ports

541uucp-rlogin542commerce545appleqtcsrvr546DHCPv6 client

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.