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18.1 Legacy Series / connection to a nonserving port on localhost
« on: July 06, 2018, 07:08:35 pm »
Hi,
I want to learn the reason why a connection to the localhost for a non-listening port not getting "connection refused".
For instance let's say port 7777 is not listening on localhost.
The command:
curl localhost:7777
does not get connection refused error, but it just waits. When I do a tcpdump all I can see is a Syn packet. No Syn+Ack or rest. When I look at the fw rules, it says that it has passed as below:
It is a clean opnsense installation, and all updates are made.
Thanks
I want to learn the reason why a connection to the localhost for a non-listening port not getting "connection refused".
For instance let's say port 7777 is not listening on localhost.
The command:
curl localhost:7777
does not get connection refused error, but it just waits. When I do a tcpdump all I can see is a Syn packet. No Syn+Ack or rest. When I look at the fw rules, it says that it has passed as below:
Code: [Select]
fw filterlog: 72,,,0,lo0,match,pass,in,4,0x0,,64,0,0,DF,6,tcp,60,127.0.0.1,127.0.0.1,10193,7777,0,S,3958098552,,65228,,mss;nop;wscale;sackOK;TS
fw filterlog: 73,,,0,lo0,match,pass,out,4,0x0,,64,0,0,DF,6,tcp,60,127.0.0.1,127.0.0.1,10193,7777,0,S,3958098552,,65228,,mss;nop;wscale;sackOK;TS
It is a clean opnsense installation, and all updates are made.
Thanks