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Port 704 (elcsd)

IANA assigns port 704 to elcsd: errlog copy/server daemon.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
elcsd TCP errlog copy/server daemon - -
elcsd UDP errlog copy/server daemon - -

Check what is listening on port 704

Linux: is anything listening on TCP 704?
sudo ss -tlnp 'sport = :704'
Linux: UDP 704
sudo ss -ulnp 'sport = :704'
Linux / macOS: which process owns the port
sudo lsof -nP -i :704
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':704 '
Windows (Command Prompt)
netstat -ano | findstr :704
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 704 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 704
From Windows
Test-NetConnection HOST -Port 704
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 704

Block port 704 in the firewall

ufw
sudo ufw deny 704/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 704 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 704 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 704' -Direction Inbound -Protocol TCP -LocalPort 704 -Action Block
ufw
sudo ufw deny 704/udp
iptables
sudo iptables -A INPUT -p udp --dport 704 -j DROP
nftables
sudo nft add rule inet filter input udp dport 704 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 704' -Direction Inbound -Protocol UDP -LocalPort 704 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.