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Help in ISA 2004

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by chaniska

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We are accessing a remote client through a VPN and when we connect to that client without the ISA the client software works perfect.

but when we route the connection through the ISA connection get dropped. (ISA 2004 SE)

What happen is as below;

from our internal network Request is generated using port 603 and when it directly goes to the client end client get it on port 513 (rlogin)
but when we route the connection through the ISA request generates from Port 603 get changed to 2XXXX range when it goes out from our router and client drops the connection (Rlogin requires the port to be lesser than 10XX)

any advice greatly appreciated.

2 replies

by robo_dev

The ISA server uses the 'call ID' to map and translate PPTP packets and pass them on to the inside network. This call id is used as the NAT mapping key.

If the router ignores the Call ID sent by remote VPN server and replace with its own Call ID, the ISA server is unable to find the correct NAT mapping and the packet is dropped by the NAT/PPTP module of ISA server.

In PPTP traffic, Call ID is important to identify the network host and transfer the data. Matching the correct Call ID is important to ensure the security of PPTP traffic.

Are you running IPSEC passthru (GRE protocol 47 support) in your router?

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