TP-Link TL-MR6400 User Manual page 64

Firewall - A firewall protects your network from the outside world. Here you can enable or

disable the router's firewall.
SPI Firewall - SPI (Stateful Packet Inspection, also known as dynamic packet filtering)

helps to prevent cyber attacks by tracking more state per session. It validates that the
traffic passing through the session conforms to the protocol. SPI Firewall is enabled by
factory default. If you want all the computers on the LAN exposed to the outside world,
you can disable it.
VPN - VPN Passthrough must be enabled if you want to allow VPN tunnels using IPSec,

PPTP, or L2TP protocols to pass through the router's firewall.
PPTP Passthrough - PPTP Passthrough. Point-to-Point Tunneling Protocol (PPTP)

allows the Point-to-Point Protocol (PPP) to be tunneled through an IP network. To
allow PPTP tunnels to pass through the router, click Enable.
L2TP Passthrough - Layer Two Tunneling Protocol (L2TP) is the method used to

enable Point-to-Point sessions via the Internet on the Layer Two level. To allow L2TP
tunnels to pass through the router, click Enable.
IPSec Passthrough - Internet Protocol security (IPSec) is a suite of protocols for

ensuring private, secure communications over Internet Protocol (IP) networks, through
the use of cryptographic security services. To allow IPSec tunnels to pass through the
router, click Enable.
ALG - It is recommended to enable Application Layer Gateway (ALG) because ALG allows

customized Network Address Translation (NAT) traversal filters to be plugged into the
TL-MR6400 300Mbps Wireless N 4G LTE Router
Figure 4-43 Basic Security
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