open5gs/docs/_docs/platform/01-debian-ubuntu.md

title
Build on Ubuntu/Debian

TUN device permissions

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To run nextepc with least privilege, the TUN device privilege should be a crw-rw-rw-(666). Otherwise, you need to run nextepc daemon as root. If the permission is not crw-rw-rw-(666), you may need to install udev package.

$ ls -al /dev/net/tun
crw-rw---- 1 root 28 10, 200 Feb 11 05:13 /dev/net/tun

$ sudo apt install udev
$ sudo systemctl start systemd-udevd (if '/lib/systemd/systemd-udevd' is not running)

$ ls -al /dev/net/tun
crw-rw-rw- 1 root 28 10, 200 Feb 11 05:13 /dev/net/tun

Nevertheless, if the permission do not change, you can run nextepc with root privileges or change the permission using chmod as follows:

$ sudo chmod 666 /dev/net/tun

Making TUN Permanent

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Write a configuration file for the TUN deivce.

$ sudo sh -c "cat << EOF > /etc/systemd/network/99-nextepc.netdev
[NetDev]
Name=pgwtun
Kind=tun
EOF"

Create a TUN device. The interface name will be pgwtun.

$ sudo systemctl enable systemd-networkd
$ sudo systemctl restart systemd-networkd

$ sudo apt install net-tools
$ ifconfig pgwtun
pgwtun: flags=4241<UP,POINTOPOINT,NOARP,MULTICAST>  mtu 1500
        inet6 fe80::e86e:86d8:ea24:f8ee  prefixlen 64  scopeid 0x20<link>
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 500  (UNSPEC)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2  bytes 255 (255.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Then, to support IPv6-enabled UEs, you must configure your TUN device to support IPv6.

$ sysctl -n net.ipv6.conf.pgwtun.disable_ipv6
1

$ sudo sh -c "echo 'net.ipv6.conf.pgwtun.disable_ipv6=0' > /etc/sysctl.d/30-nextepc.conf"
$ sudo sysctl -p /etc/sysctl.d/30-nextepc.conf

$ sysctl -n net.ipv6.conf.pgwtun.disable_ipv6
0

Note: If your TUN device already supports IPv6, you can skip this steps above. {: .notice--warning}

You are now ready to set the IP address on TUN device.

$ sudo sh -c "cat << EOF > /etc/systemd/network/99-nextepc.network
[Match]
Name=pgwtun
[Network]
Address=45.45.0.1/16
Address=cafe::1/64
EOF"

Restart the TUN device

$ sudo systemctl restart systemd-networkd

Make sure it is set up properly.

$ ifconfig pgwtun
pgwtun: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1500
        inet 45.45.0.1  netmask 255.255.0.0  destination 45.45.0.1
        inet6 cafe::1  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::e86e:86d8:ea24:f8ee  prefixlen 64  scopeid 0x20<link>
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 500  (UNSPEC)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 20  bytes 2019 (2.0 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Note: On Linux, you should run nextepc-pgwd first to correctly verify the IP address of TUN device. Otherwise, the TUN device's IP address is not displayed by the ifconfig command. {: .notice--warning}