When the first fragment arrives, the NAT device successfully translates the address information in the IP header, and port information in the UDP header and forwards the packet.
The NATing device does not know how to wait for all the fragments, reassemble and NAT them. The second fragment consists of only the IP header and the second data fragment. The first fragment consists of the IP header plus the UDP header and some portion of the data. For example, if the UDP packet is too long, the remote client fragments the packet. Hide NAT not only changes the IP header but also the port information contained in the UDP header. Problems arise when the remote access client is behind a hide NAT device that does not support this kind of packet fragmentation: If the resulting packets are greater than the MTU, the packets are fragmented at the Data Link layer of the Operating System's TCP/IP stack. When a remote access client attempts to create a VPN tunnel with its peer Security Gateway, the IKE or IPsec packets may be larger than the Maximum Transmission Unit (MTU) value. NAT related issues arise with hide NAT devices that do not support packet fragmentation. Other issues, such as Domain Name Resolution involving DNS servers found on an internal network protected by a Security Gateway Dedicated Check Point server that runs Check Point software to inspect traffic and enforce Security Policies for connected network resources., are resolved with Split DNS (see Split DNS). Routing issues of this type are resolved using Office Mode (see Office Mode).
Other connectivity issues can arise, for example when a remote client receives an IP address that matches an IP on the internal network. IPsec Path Maximum Transmission Unit ( IPsec PMTU)Ĭheck Point resolves port filtering issues with Visitor Mode (formally: TCP Tunneling). Issues involving service/port filtering on the enforcement deviceĬheck Point Solution for Connectivity IssuesĬheck Point resolves NAT related connectivity issues with a number of features: Issues involving NAT devices that do not support fragmentation. Under these conditions, a number of connectivity issues can arise: During the morning they may be located within the network of a partner company, the following evening connected to a hotel LAN or behind some type of enforcement or NATing device. Remote clients are, by their nature, mobile. While there are a few connectivity issues regarding VPN between Security Gateways, remote access clients present a special challenge.
Resolving Connectivity Issues The Need for Connectivity Resolution Features
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