OPNsense Forum

Archive => 18.1 Legacy Series => Topic started by: svn on July 06, 2018, 07:08:35 pm

Title: connection to a nonserving port on localhost
Post by: svn 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:

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

Title: Re: connection to a nonserving port on localhost
Post by: kanstin on July 08, 2018, 01:25:59 am

My guess is you would need to add a rule to firewall to allow the connection.