A followup to this question.
I have a Cisco 877 ADSL router configured (at last!) to act as a VPN server; it supports both PPTP and L2TP VPNs, and I can successfully connect to it from Windows computers using the built-in VPN software.
There is only one problem: when using a PPTP VPN, encryption doesn't work. If I configure the client to require encryption (default setting), the connection fails with an error about the remote endpoint not supporting it. If I remove the encryption requirement, the connection succeeds. I've also tried tweaking the encryption settings (40/128 bits), but this didn't work either.
This is the relevant part of the router's configuration; the complete config is available in the question I linked above.
vpdn enable vpdn-group VPN_Clients accept-dialin protocol any virtual-template 1 ip local pool VPN_Pool 192.168.42.250 192.168.42.254 interface Virtual-Template1 ip unnumbered Vlan1 ip nat inside peer default ip address pool VPN_Pool ppp encrypt mppe auto required ppp authentication ms-chap-v2 ms-chap chap
The router's IOS version is 15, and it fully supports encryption.
The strangest thing is, encryption is actually required in the router config; but not only the router doesn't seem to offer it... it also accepts unencrypted connections, which it shouldn't. It's like the
ppp encrypt mppe auto required command is completely ignored.
How can I fix this?