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Debugging openfortivpn

Run openfortivpn in verbose mode using command line option -v (or even -v -v for very verbose output).
Retrieve the pppd log using command line option --pppd-log. Some issues are related to pppd which is forked by openfortivpn.

Reporting issues

Create a new ticket under Issues instead of adding comments to existing issues. Similar symptoms do not necessarily mean identical causes.
Specify the versions of the operating system and openfortivpn.
Provide the verbose openfortivpn output obtained with command line option -v and the pppd log obtained with command line option --pppd-log. Remember to redact confidential information such as IP addresses.

starting openfortivpn as a system service

StandardOutput= should redirect the output of openfortivpn to a file.
With Type=simple the PID of openfortivpn should be known to systemd.
Restart= can be used instead of --persistent.

using pppd ip-up / ip-down scripts

pppd sets a couple of environment variables (see man pppd). ipparam is currently passed through openfortivpn, but inside the ip-up / ip-down scripts one can replace variables in this string as follows:

ipparam_raw=$6
ipparam=$(eval echo $ipparam_raw)

and invoke with openfortivpn --pppd-ipparam='device=$DEVICE' Note the single quotes to prevent from variable expansion by the calling shell where $DEVICE is not yet set. Expansion is done inside the script by the execution of eval echo $ipparam_raw when the environment variables are made available by pppd.

One application is to manage the update of /etc/resolv.conf using openresolv. When calling openfortivpn --no-dns -v with the following scripts present on the system /etc/ppp/ip-down.d/000resolvconf:

#!/bin/sh
 
[ -x /sbin/resolvconf ] || exit 0
/sbin/resolvconf -f -d "$PPP_IFACE"

and /etc/ppp/ip-up.d/000resolvconf:

#!/bin/sh

[ -x /sbin/resolvconf ] || exit 0

if [ -n "$DNS1" -o -n "$DNS2" ]; then
        conf="# Generated by ppp.ip-up for $PPP_IFACE\n"
        [ -n "$DNS1" ] && conf="${conf}nameserver $DNS1\n"
        [ -n "$DNS2" ] && conf="${conf}nameserver $DNS2\n"
        printf "$conf" | /sbin/resolvconf -a "$PPP_IFACE"
fi

See also pppd ip-up scripts and option --pppd-ipparam in the openfortivpn man page.

How to add specific routes using pppd

run openfortivpn with --no-route flag, or add set-routes = 0 in your configuration file
create a ppp script when link is up: sudo touch /etc/ppp/ip-up.d/fortivpn
make it executable: sudo chmod a+x /etc/ppp/ip-up.d/fortivpn
add your own routes, either by look up of their name or by adding specific ip addresses:

    #!/bin/bash
    #
    # Whitelist here all domains that need to go through openfortivpn
    # Domains are separated by a space
    #
    domains='example.com example.fr'
    ips='192.168.0.15'
    
    let resolved
    for domain in $domains; do
      resolved=`dig +short $domain | tail -n1`
      ips="$ips $resolved"
    done
    
    for ip in $ips; do
      route add $ip dev ppp0
    done

check the created routes:

    $ route
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    default         192.168.10.254  0.0.0.0         UG    600    0        0 wlp3s0
    one.one.one.one *               255.255.255.255 UH    0      0        0 ppp0
    IP-OF-FIRST-DOMAIN *               255.255.255.255 UH    0      0        0 ppp0
    IP-OF-SECOND-DOMAIN *               255.255.255.255 UH    0      0        0 ppp0
    link-local      *               255.255.0.0     U     1000   0        0 br-cc6b09fa8986
    172.16.238.0    *               255.255.255.0   U     0      0        0 br-30ec352ff3e1
    172.17.0.0      *               255.255.0.0     U     0      0        0 docker0
    172.18.0.0      *               255.255.0.0     U     0      0        0 br-44b22a74e13d
    172.19.0.0      *               255.255.0.0     U     0      0        0 br-cc6b09fa8986
    172.20.0.0      *               255.255.0.0     U     0      0        0 br-2718c069c2ed
    192.168.10.0    *               255.255.255.0   U     600    0        0 wlp3s0

check your IP: https://duckduckgo.com/?q=what%27s+my+ip&t=lm&atb=v110-5_h&ia=answer It should be your regular IP, while you should have access to white-listed domains through the VPN.

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