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Do I really need a firewall for my server? (sopuli.xyz)
submitted 1 year ago by theselfhoster@sopuli.xyz to c/selfhosted@lemmy.world
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I've been running my server without a firewall for quite some time now, I have a piped instance and snikket running on it. I've been meaning to get UFW on it but I've been too lazy to do so. Is it a necessary thing that I need to have or it's a huge security vulnerability? I can only SSH my server from only my local network and must use a VPN if I wanna SSH in outside so I'd say my server's pretty secure but not the furthest I could take it. Opinions please?

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[-] ShellMonkey@lemmy.socdojo.com -1 points 1 year ago

NAT in the sense used when people talk about at home is a source nat, or as we like to call it in the office space a hide address, everyone going to the adjacent net appears to be the same source IP and the system maintains a table of connections to correlate return traffic to.

The other direction though, if you where on that upstream net and tried to target traffic towards the SNAT address above the router has no idea where to send it to unless there's a map to designate where incoming connections need to be sent on the other side of the NAT so it ends up being dropped. I suppose in theory it could try and send it to everyone in the local side net, but if you get multiple responses everything is going to get hosed up.

So from the perspective of session state initiation it can act as a firewall since without route maps it only will work from one side.

this post was submitted on 24 Mar 2025
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