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Old 02-06-2008, 03:14 PM   #1
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Inbound vs Outbound ports?

what is the difference between inbound (ingress) and outbound(egress) in tcp?

i am using apf firewall, just confused about opening port 22 (SSH) for both inbound and outbound.

i experimented only allowing inbound and SSH works fine. But then again , how do i understand inbound and outbound?
Old 02-06-2008, 03:20 PM   #2
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If its anything like iptables with inbound and outbound. Inbound is connections coming to the device from remote locations(including the localhost). Outbound is if the localhost was going to send data packets to a destination port of 22(ssh) those packets can be stopped and dropped. Meaning you could stop anyone connecting to port 22 on a remote device from the localhost, not always that useful as of course ssh and most server services can run on any port number you specify as long as its free. All depends on what you might use it for

Hope its useful
Old 02-06-2008, 03:38 PM   #3
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wonderful answer thanks

i am using putty to connect to ssh. so that means putty is also running at 22 in my windows xp computer or it connects through port 80. i am remotely logging to my server.

what all services in linux server require both inbound and outbound?

Last edited by olddocks; 02-06-2008 at 03:39 PM.
Old 02-10-2008, 12:19 AM   #4
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Point of view from the client:
Connecting to an SSH server would be an outbound connection.

Point of view from the server:
A client connecting to you would be an inbound connection.

Telling APF (that is running on your Linux box) to allow port 22 inbound is basically telling it that you have an SSH server running on your Linux box and want others to get a shell that is running on your Linux box.
Telling APF that you want to allow outbound connections means that you want to connect from your Linux box to an SSH server running elsewhere (perhaps on your XP box?)

Last edited by t1n0m3n; 02-10-2008 at 12:32 AM.


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