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Port 157 (knet-cmp)

IANA assigns port 157 to knet-cmp: KNET/VM Command/Message Protocol.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
knet-cmp TCP KNET/VM Command/Message Protocol Gary S Malkin -
knet-cmp UDP KNET/VM Command/Message Protocol Gary S Malkin -

Check what is listening on port 157

Linux: is anything listening on TCP 157?
sudo ss -tlnp 'sport = :157'
Linux: UDP 157
sudo ss -ulnp 'sport = :157'
Linux / macOS: which process owns the port
sudo lsof -nP -i :157
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':157 '
Windows (Command Prompt)
netstat -ano | findstr :157
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 157 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 157
From Windows
Test-NetConnection HOST -Port 157
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 157

Block port 157 in the firewall

ufw
sudo ufw deny 157/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 157 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 157 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 157' -Direction Inbound -Protocol TCP -LocalPort 157 -Action Block
ufw
sudo ufw deny 157/udp
iptables
sudo iptables -A INPUT -p udp --dport 157 -j DROP
nftables
sudo nft add rule inet filter input udp dport 157 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 157' -Direction Inbound -Protocol UDP -LocalPort 157 -Action Block

Related ports

155netsc-dev156sqlsrv158pcmail-srv159nss-routing

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