I'm having a trouble. I use winXP to connect through L2TP/IPsec to one Linux server. When I try to connect in my domain appear an error at log. Plugin winbind.so loaded. WINBIND plugin initialized. using channel 36 Using interface ppp1 Connect: ppp1 <--> /dev/pts/3 sent [LCP ConfReq id=0x1 <mru 1410> <asyncmap 0x0> <auth chap MD5> <magic 0x564e3dc9> <pcomp> <accomp>] rcvd [LCP ConfReq id=0x0 <mru 1400> <magic 0x17201f33> <pcomp> <accomp> <callback CBCP>] sent [LCP ConfRej id=0x0 <callback CBCP>] rcvd [LCP ConfAck id=0x1 <mru 1410> <asyncmap 0x0> <auth chap MD5> <magic 0x564e3dc9> <pcomp> <accomp>] rcvd [LCP ConfReq id=0x1 <mru 1400> <magic 0x17201f33> <pcomp> <accomp>] sent [LCP ConfAck id=0x1 <mru 1400> <magic 0x17201f33> <pcomp> <accomp>] sent [CHAP Challenge id=0x97 <7eec83d8710952cf7dd2429904906dca727e>, name = "VPNserver"] rcvd [LCP code=0xc id=0x2 17 20 1f 33 4d 53 52 41 53 56 35 2e 31 30] sent [LCP CodeRej id=0x2 0c 02 00 12 17 20 1f 33 4d 53 52 41 53 56 35 2e 31 30] rcvd [LCP code=0xc id=0x3 17 20 1f 33 4d 53 52 41 53 2d 30 2d 4d 30 30 31] sent [LCP CodeRej id=0x3 0c 03 00 14 17 20 1f 33 4d 53 52 41 53 2d 30 2d 4d 30 30 31] rcvd [CHAP Response id=0x97 <02b7ac982f9050bb1272945451f4bd41>, name "CASA\\anapaula"] WINBIND: Challenge type 5 unsupported Peer CASA\\anapaula failed CHAP authentication sent [CHAP Failure id=0x97 ""] sent [LCP TermReq id=0x4 "Authentication failed"] rcvd [LCP TermAck id=0x4 "Authentication failed"] Connection terminated. Plugin winbind.so loaded. WINBIND plugin initialized. using channel 37 Using interface ppp1 Connect: ppp1 <--> /dev/pts/3 sent [LCP ConfReq id=0x1 <mru 1410> <asyncmap 0x0> <auth chap MD5> <magic 0x2eb0c923> <pcomp> <accomp>] rcvd [LCP ConfAck id=0x1 <mru 1410> <asyncmap 0x0> <auth chap MD5> <magic 0x2eb0c923> <pcomp> <accomp>] rcvd [LCP ConfReq id=0x1 <mru 1400> <magic 0x1adf15ed> <pcomp> <accomp> <callback CBCP>] sent [LCP ConfRej id=0x1 <callback CBCP>] rcvd [LCP ConfReq id=0x2 <mru 1400> <magic 0x1adf15ed> <pcomp> <accomp>] sent [LCP ConfAck id=0x2 <mru 1400> <magic 0x1adf15ed> <pcomp> <accomp>] sent [CHAP Challenge id=0xc5 <d2a61dabfd2d51e4ec7af881df2b7db463822d>, name = "VPNserver"] rcvd [LCP code=0xc id=0x3 1a df 15 ed 4d 53 52 41 53 56 35 2e 31 30] sent [LCP CodeRej id=0x2 0c 03 00 12 1a df 15 ed 4d 53 52 41 53 56 35 2e 31 30] rcvd [LCP code=0xc id=0x4 1a df 15 ed 4d 53 52 41 53 2d 30 2d 4d 30 30 31] sent [LCP CodeRej id=0x3 0c 04 00 14 1a df 15 ed 4d 53 52 41 53 2d 30 2d 4d 30 30 31] rcvd [CHAP Response id=0xc5 <aca27dcad56ab3d6a4b023a61e708be3>, name "CASA\\anapaula"] WINBIND: Challenge type 5 unsupported Peer CASA\\anapaula failed CHAP authentication sent [CHAP Failure id=0xc5 ""] sent [LCP TermReq id=0x4 "Authentication failed"] rcvd [LCP TermAck id=0x4 "Authentication failed"] Connection terminated. I'm using: Fedora 2.6.12-1.1398_FC4 ppp-2.4.3-5.fc4 options file: ipcp-accept-local ipcp-accept-remote ms-dns 192.168.99.1 ms-wins 192.168.99.4 noccp auth crtscts idle 1800 mtu 1410 mru 1410 nodefaultroute debug lock proxyarp connect-delay 5000 logfile /var/log/l2tpd.log plugin winbind.so ntlm_auth-helper "/usr/bin/ntlm_auth --helper-protocol=ntlm-server-1" I execute the command [root@f001 ppp]# /usr/bin/ntlm_auth --helper-protocol=ntlm-server-1 Full-Username: CASA\anapaula Password: a9n8a68 . Authenticated: Yes Marcos