vpnc - client for Cisco VPN3000 Concentrator, IOS and PIX
vpnc [
--version] [
--print-config] [
--help]
[
--long-help] [
options] [
config files]
This manual page documents briefly the
vpnc and
vpnc-disconnect
commands.
vpnc is a VPN client for the Cisco 3000 VPN Concentrator, creating a
IPSec-like connection as a tunneling network device for the local system. It
uses the TUN/TAP driver in Linux kernel 2.4 and above and device tun(4) on
BSD. The created connection is presented as a tunneling network device to the
local system.
OBLIGATORY WARNING: the most used configuration (XAUTH authentication with
pre-shared keys and password authentication) is insecure by design, be aware
of this fact when you use vpnc to exchange sensitive data like passwords!
The vpnc daemon by itself does not set any routes, but it calls
vpnc-script to do this job.
vpnc-script displays a connect
banner. If the concentrator supplies a network list for split-tunneling these
networks are added to the routing table. Otherwise the default-route will be
modified to point to the tunnel. Further a host route to the concentrator is
added in the later case. If the client host needs DHCP, care must be taken to
add another host route to the DHCP-Server around the tunnel.
The
vpnc-disconnect command is used to terminate the connection
previously created by
vpnc and restore the previous routing
configuration.
The daemon reads configuration data from the following places:
- •
- command line options
- •
- config file(s) specified on the command line
- •
- /usr/local/etc/vpnc/default.conf
- •
- /usr/local/etc/vpnc.conf
- •
- prompting the user if not found above
vpnc can parse options and
configuration files in any order. However the
first place to set an option wins. configuration filenames which do not
contain a / will be searched at
/usr/local/etc/vpnc/<filename>
and
/usr/local/etc/vpnc/<filename>.conf. Otherwise
<filename> and
<filename>.conf will be used. If no
configuration file is specified on the command-line at all, both
/usr/local/etc/vpnc/default.conf and
/usr/local/etc/vpnc.conf
will be loaded.
The program options can be either given as arguments (but not all of them for
security reasons) or be stored in a configuration file.
- --gateway <ip/hostname>
- IP/name of your IPSec gateway
conf-variable:
IPSec gateway <ip/hostname>
- --id <ASCII string>
- your group name
conf-variable:
IPSec ID <ASCII string>
- (configfile only option)
- your group password (cleartext)
conf-variable:
IPSec secret <ASCII string>
- (configfile only option)
- your group password (obfuscated)
conf-variable:
IPSec obfuscated secret <hex string>
- --username <ASCII string>
- your username
conf-variable:
Xauth username <ASCII string>
- (configfile only option)
- your password (cleartext)
conf-variable:
Xauth password <ASCII string>
- (configfile only option)
- your password (obfuscated)
conf-variable:
Xauth obfuscated password <hex string>
- --domain <ASCII string>
- (NT-) Domain name for authentication
conf-variable:
Domain <ASCII string>
- --xauth-inter
- enable interactive extended authentication (for challenge response
auth)
conf-variable:
Xauth interactive
- --vendor <cisco/netscreen>
- vendor of your IPSec gateway
- Default: cisco
conf-variable:
Vendor <cisco/netscreen>
- --natt-mode <natt/none/force-natt/cisco-udp>
- Which NAT-Traversal Method to use:
- •
- natt -- NAT-T as defined in RFC3947
- •
- none -- disable use of any NAT-T method
- •
- force-natt -- always use NAT-T encapsulation even without presence of a
NAT device (useful if the OS captures all ESP traffic)
- •
- cisco-udp -- Cisco proprietary UDP encapsulation, commonly over Port
10000
- Note: cisco-tcp encapsulation is not yet supported
- Default: natt
conf-variable:
NAT Traversal Mode
<natt/none/force-natt/cisco-udp>
- --script <command>
- command is executed using system() to configure the interface, routing and
so on. Device name, IP, etc. are passed using enviroment variables, see
README. This script is executed right after ISAKMP is done, but before
tunneling is enabled. It is called when vpnc terminates, too
- Default: /usr/local/sbin/vpnc-script
conf-variable:
Script <command>
- --dh <dh1/dh2/dh5>
- name of the IKE DH Group
- Default: dh2
conf-variable:
IKE DH Group <dh1/dh2/dh5>
- --pfs <nopfs/dh1/dh2/dh5/server>
- Diffie-Hellman group to use for PFS
- Default: server
conf-variable:
Perfect Forward Secrecy
<nopfs/dh1/dh2/dh5/server>
- --enable-1des
- enables weak single DES encryption
conf-variable:
Enable Single DES
- --enable-no-encryption
- enables using no encryption for data traffic (key exchanged must be
encrypted)
conf-variable:
Enable no encryption
- --application-version <ASCII string>
- Application Version to report. Note: Default string is generated at
runtime.
- Default: Cisco Systems VPN Client 0.5.3:FreeBSD
conf-variable:
Application version <ASCII string>
- --ifname <ASCII string>
- visible name of the TUN/TAP interface
conf-variable:
Interface name <ASCII string>
- --ifmode <tun/tap>
- mode of TUN/TAP interface:
- •
- tun: virtual point to point interface (default)
- •
- tap: virtual ethernet interface
- Default: tun
conf-variable:
Interface mode <tun/tap>
- --debug <0/1/2/3/99>
- Show verbose debug messages
- •
-
0: Do not print debug information.
- •
-
1: Print minimal debug information.
- •
-
2: Show statemachine and packet/payload type information.
- •
-
3: Dump everything exluding authentication data.
- •
- 99: Dump everything INCLUDING AUTHENTICATION data (e.g. PASSWORDS).
conf-variable:
Debug <0/1/2/3/99>
- --no-detach
- Don't detach from the console after login
conf-variable:
No Detach
- --pid-file <filename>
- store the pid of background process in <filename>
- Default: /var/run/vpnc/pid
conf-variable:
Pidfile <filename>
- --local-addr <ip/hostname>
- local IP to use for ISAKMP / ESP / ... (0.0.0.0 == automatically
assign)
- Default: 0.0.0.0
conf-variable:
Local Addr <ip/hostname>
- --local-port <0-65535>
- local ISAKMP port number to use (0 == use random port)
- Default: 500
conf-variable:
Local Port <0-65535>
- --udp-port <0-65535>
- Local UDP port number to use (0 == use random port). This is only relevant
if cisco-udp nat-traversal is used. This is the _local_ port, the remote
udp port is discovered automatically. It is especially not the cisco-tcp
port.
- Default: 10000
conf-variable:
Cisco UDP Encapsulation Port <0-65535>
- --dpd-idle <0,10-86400>
- Send DPD packet after not receiving anything for <idle> seconds. Use
0 to disable DPD completely (both ways).
- Default: 300
conf-variable:
DPD idle timeout (our side) <0,10-86400>
- --non-inter
- Don't ask anything, exit on missing options
conf-variable:
Noninteractive
- --auth-mode <psk/cert/hybrid>
- Authentication mode:
- •
- psk: pre-shared key (default)
- •
- cert: server + client certificate (not implemented yet)
- •
- hybrid: server certificate + xauth (if built with openssl support)
- Default: psk
conf-variable:
IKE Authmode <psk/cert/hybrid>
- --ca-file <filename>
- filename and path to the CA-PEM-File
conf-variable:
CA-File <filename>
- --ca-dir <directory>
- path of the trusted CA-Directory
- Default: /etc/ssl/certs
conf-variable:
CA-Dir <directory>
- --target-network <target network/netmask>
- Target network in dotted decimal or CIDR notation
- Default: 0.0.0.0/0.0.0.0
conf-variable:
IPSEC target network <target network/netmask>
--print-config
- Prints your configuration; output can be used as vpnc.conf
/usr/local/etc/vpnc.conf /usr/local/etc/vpnc/default.conf
The default configuration file. You can specify the same
config directives as with command line options and additionaly
IPSec
secret and
Xauth password both supplying a cleartext password.
Scrambled passwords from the Cisco configuration profiles can be used with
IPSec obfuscated secret and
Xauth obfuscated password.
See
EXAMPLES for further details.
/usr/local/etc/vpnc/*.conf
vpnc will read configuration files in this directory when
the config filename (with or without .conf) is specified on the command
line.
This is an example vpnc.conf with pre-shared keys:
IPSec gateway vpn.example.com
IPSec ID ExampleVpnPSK
IKE Authmode psk
IPSec secret PskS3cret!
Xauth username user@example.com
Xauth password USecr3t
And another one with hybrid authentication (requires that vpnc was built with
openssl support):
IPSec gateway vpn.example.com
IPSec ID ExampleVpnHybrid
IKE Authmode hybrid
CA-Dir /usr/local/etc/vpnc
or
CA-File /usr/local/etc/vpnc/vpn-example-com.pem
IPSec secret HybS3cret?
Xauth username user@example.com
Xauth password 123456
The lines begin with a keyword (no leading spaces!). The values start exactly
one space after the keywords, and run to the end of line. This lets you put
any kind of weird character (except CR, LF and NUL) in your strings, but it
does mean you can't add comments after a string, or spaces before them.
In case the the
CA-Dir option is used, your certificate needs to be named
something like 722d15bd.X, where X is a manually assigned number to make sure
that files with colliding hashes have different names. The number can be
derived from the certificate file itself:
openssl x509 -subject_hash -noout -in /usr/local/etc/vpnc/vpn-example-com.pem
See also the
--print-config option to generate a config file, and the
example file in the package documentation directory where more advanced usage
is demonstrated.
Advanced features like manual setting of multiple target routes and disabling
/etc/resolv.conf rewriting is documented in the README of the vpnc package.
Certificate support (Pre-Shared-Key + XAUTH is known to be insecure).
Further points can be found in the TODO file.
This man-page has been written by Eduard Bloch <blade(at)debian.org> and
Christian Lackas <delta(at)lackas.net>, based on vpnc README by Maurice
Massar <vpnc(at)unix-ag.uni-kl.de>. Permission is granted to copy,
distribute and/or modify this document under the terms of the GNU General
Public License, Version 2 any later version published by the Free Software
Foundation.
On Debian systems, the complete text of the GNU General Public License can be
found in /usr/share/common-licenses/GPL.
pcf2vpnc(1),
cisco-decrypt(1),
ip(8),
ifconfig(8),
route(1),
http://www.unix-ag.uni-kl.de/~massar/vpnc/