Troubleshooting: Issues with Outbound Traffic from tun0 IP

[seralydotnet]

Create a TUN/TAP device named tun0 in "tun" mode
ip tuntap add mode tun dev tun0

Assign an IP address (198.18.0.1/15) to the tun0 device
ip addr add 198.18.0.1/15 dev tun0

Activate the tun0 device
ip link set dev tun0 up

Delete the default route
ip route del default

Add a new default route via 198.18.0.1 through the tun0 device with a metric of 1
ip route add default via 198.18.0.1 dev tun0 metric 1

Add another default route via 192.168.1.1 through the eth0 device with a metric of 10
ip route add default via 192.168.1.1 dev eth0 metric 10

Redirect network traffic from tun0 to a SOCKS5 proxy at host:port, with eth0 as the outgoing interface
tun2socks -device tun0 -proxy socks5://host:port -interface eth0

Disable Reverse Path Filtering for better network routing

sysctl net.ipv4.conf.all.rp_filter=0
sysctl net.ipv4.conf.eth0.rp_filter=0

Perform a cURL request from eth0
curl -v --interface eth0 http://ipinfo.io/
This works

Perform a cURL request from 192.168.1.1
curl -v --interface 192.168.1.1 http://ipinfo.io/
This also works

Perform a cURL request from tun0
curl -v --interface tun0 http://ipinfo.io/
This works

Perform a cURL request from 198.18.0.1
curl -v --interface 198.18.0.1 http://ipinfo.io/
This does not work and times out

Ping test from eth0
ping -c 8 -v4 -I eth0 ipinfo.io
This works

Ping test from 192.168.1.1
ping -c 8 -v4 -I 192.168.1.1 ipinfo.io
This also works

Ping test from tun0
ping -c 8 -v4 -I tun0 ipinfo.io
This works

Ping test from 198.18.0.1
ping -c 8 -v4 -I 198.18.0.1 ipinfo.io
This does not work and times out

Firewall status: OFF