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Port 6455 (skip-cert-recv)

IANA assigns port 6455 to skip-cert-recv: SKIP Certificate Receive.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
skip-cert-recv TCP SKIP Certificate Receive Tom Markson -
skip-cert-recv UDP SKIP Certificate Receive Tom Markson -

Check what is listening on port 6455

Linux: is anything listening on TCP 6455?
sudo ss -tlnp 'sport = :6455'
Linux: UDP 6455
sudo ss -ulnp 'sport = :6455'
Linux / macOS: which process owns the port
sudo lsof -nP -i :6455
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':6455 '
Windows (Command Prompt)
netstat -ano | findstr :6455
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 6455 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 6455
From Windows
Test-NetConnection HOST -Port 6455
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 6455

Block port 6455 in the firewall

ufw
sudo ufw deny 6455/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 6455 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 6455 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 6455' -Direction Inbound -Protocol TCP -LocalPort 6455 -Action Block
ufw
sudo ufw deny 6455/udp
iptables
sudo iptables -A INPUT -p udp --dport 6455 -j DROP
nftables
sudo nft add rule inet filter input udp dport 6455 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 6455' -Direction Inbound -Protocol UDP -LocalPort 6455 -Action Block

Related ports

6445sge-execd, sge_execd6446mysql-proxy6456skip-cert-send6464ieee11073-20701

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