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Port 5251 (caevms)

IANA assigns port 5251 to caevms: CA eTrust VM Service.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
caevms TCP CA eTrust VM Service Kevin Bond -
caevms UDP CA eTrust VM Service Kevin Bond -

Registry dates for this port: registered 2004-11.

Check what is listening on port 5251

Linux: is anything listening on TCP 5251?
sudo ss -tlnp 'sport = :5251'
Linux: UDP 5251
sudo ss -ulnp 'sport = :5251'
Linux / macOS: which process owns the port
sudo lsof -nP -i :5251
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':5251 '
Windows (Command Prompt)
netstat -ano | findstr :5251
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 5251 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 5251
From Windows
Test-NetConnection HOST -Port 5251
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 5251

Block port 5251 in the firewall

ufw
sudo ufw deny 5251/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 5251 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 5251 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 5251' -Direction Inbound -Protocol TCP -LocalPort 5251 -Action Block
ufw
sudo ufw deny 5251/udp
iptables
sudo iptables -A INPUT -p udp --dport 5251 -j DROP
nftables
sudo nft add rule inet filter input udp dport 5251 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 5251' -Direction Inbound -Protocol UDP -LocalPort 5251 -Action Block

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5249caaclang25250soagateway5252movaz-ssc5253kpdp

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