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97 lines
4.1 KiB
Markdown
97 lines
4.1 KiB
Markdown
---
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layout: post
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comments: true
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title: "My ufw (Ubuntu/Uncomplicated Firewall) config"
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category: [english]
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tags: [english]
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redirect_from:
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- /ufw/
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- /english/2015/06/12/ufw.html
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---
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*This post describes my UFW config and is here so I find it from somewhere
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and with hope that I am told if someone notices something terriby insecure
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here and is able to offer suggestions. This probably will never be
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perfect.*
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Having firewall is important as you aren't always in your trusted home
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network (that can also be broken into especially if you have WLAN) and
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with IPv6 your devices have public IPv6 addresses. Theoretically your
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router should include a firewall, but at least the Huawei mobile broadband
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routers or MiFis don't include one (and I might be annoyed by it enough
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to disable it anyway and configure everything on host level if it was
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my network).
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*Threat model: service I am not aware of or that I accidentally make
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listen wider than intended, with UFW I am aware of what ports are
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allowed. I assume any mobile host is going to move randomly and while
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some whitelists (especially link-local and IPv4 LANs) will overlap and
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possibly allow access, it's still better than being open to the internet
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and overlay networks that I have interacted with recently.*
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This post first has list of commands, then explanations that won't be
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repeated with IPvX ranges.
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```bash
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ufw allow 22/tcp
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ufw default deny incoming
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ufw default allow outgoing
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systemctl enable ufw && systemctl start ufw
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ufw enable
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ufw reject 113/tcp
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#ufw allow from 192.168.8.0/24 to any port 631 proto tcp
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ufw allow from fe80::/10 to any port 631
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#ufw allow from 192.168.8.0/24 to any port 5353 proto udp
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ufw allow from fe80::/10 to any port 5353 proto udp
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#ufw allow from <static:Yggdrasil:IPv6> to any port 5900
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ufw allow from fe80::/10 to any port 9001 proto udp
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ufw allow 60000:61000/udp
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```
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* 22 TCP/ssh — Allow acces to SSHd you don't want to lock yourself out.
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* previously I used `ufw limit` but it seems to be too oversensitive,
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just use SSHGuard.
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* Deny incoming connections unless the port has been whitelisted.
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* Allow all outgoing connections, keeping list of authorized ports would
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be too much for me.
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* Start ufw on boot and now (I am not sure if this step is required, but
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better safe than sorry).
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* Put the firewall in force.
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* 113 TCP/ident — Tell "Connection refused" to whoever tries to reach port
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113. This makes ident checking IRC servers connect faster as they don't
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have to timeout. If you run shell server (for IRC purpouses) you should
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allow this instead. And if you don't use IRC or don't care about having
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to wait for the check to timeout, don't do this as you may leave
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yourself visible to random port scanners.
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* 631 both/cups — Allow access to cups for printer sharing from 192.168.8.xxx
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* fe80:://10 is link-local address existing _everywhere_ IPv6 is enabled,
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check your `ip addr` or on Windows `ipconfig /all` for fun.
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* 5353 UDP/mdns/Avahi — used for `.local` addresses.
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* 5900 — VNC port at least for `krfb kdrc` (KDE Remote Desktop server & client).
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I tend to only allow it from specific Yggdrasil address(es).
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* 9001/udp — [Yggdrasil](https://yggdrasil-network.github.io/) automatic
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peering port only on link-local.
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* 60000:61000 UDP/mosh — I feel this is the most insecure part of this
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setup and there should be something bettter instead of this. As
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something evil could run and listen on these ports.
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*If some host doesn't run some of the mentioned service, it's not open in
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the firewall.*
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KDE Connect which seems painful enough to list separately and doesn't seem
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to work IPv6-only or I am too impatient.
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```bash
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#ufw allow from 192.168.8.0/24 to any port 1714:1764 proto tcp
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#ufw allow from 192.168.8.0/24 to any port 1714:1764 proto udp
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ufw allow from fe80::/10 to any port 1714:1764 proto tcp
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ufw allow from fe80::/10 to any port 1714:1764 proto udp
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```
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* * * * *
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Last updated: 2018-11-03T13:25+0200 | [GitHub changelog](https://github.com/Mikaela/mikaela.github.io/commits/master/_posts/2015-06-12-ufw.md) |
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[Blesmrt Gitea changelog](https://gitea.blesmrt.net/mikaela/mikaela-info/commits/branch/master/_posts/2015-06-12-ufw.md)
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