Eu tenho um erro quando estou tentando instalar o L2TP .. qualquer um pode me ajudar .. resolver este issuse

root@t-Aspire-5742:/# sudo ipsec verify

Checking your system to see if IPsec got installed and started correctly:
Version check and ipsec on-path                                 [OK]

Linux Openswan U2.6.37/K3.5.0-42-generic (netkey)
Checking for IPsec support in kernel                            [OK]

 SAref kernel support                                           [N/A]

 NETKEY:  Testing XFRM related proc values                      [FAILED]

  Please disable /proc/sys/net/ipv4/conf/*/send_redirects
  or NETKEY will cause the sending of bogus ICMP redirects! [FAILED]

  Please disable /proc/sys/net/ipv4/conf/*/accept_redirects
  or NETKEY will accept bogus ICMP redirects                    [OK]

Checking that pluto is running                                  [OK]

 Pluto listening for IKE on udp 500                             [OK]

 Pluto listening for NAT-T on udp 4500                          [OK]

Two or more interfaces found, checking IP forwarding            [FAILED]

Checking for 'ip' command                                       [OK]

Checking /bin/sh is not /bin/dash                               [WARNING]

Checking for 'iptables' command                                 [OK]

Opportunistic Encryption Support                                [DISABLED]

Você precisa desativar o envio e aceitar:

# Disable send redirects
echo 0 > /proc/sys/net/ipv4/conf/all/send_redirects
echo 0 > /proc/sys/net/ipv4/conf/default/send_redirects
echo 0 > /proc/sys/net/ipv4/conf/eth0/send_redirects
echo 0 > /proc/sys/net/ipv4/conf/lo/send_redirects

# Disable accept redirects
echo 0 > /proc/sys/net/ipv4/conf/all/accept_redirects
echo 0 > /proc/sys/net/ipv4/conf/default/accept_redirects
echo 0 > /proc/sys/net/ipv4/conf/eth0/accept_redirects
echo 0 > /proc/sys/net/ipv4/conf/lo/accept_redirects

Para torná-lo permanente na reinicialização, no sysctl.conf, coloque as linhas abaixo

net.ipv4.conf.all.accept_redirects = 0 
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.eth0.accept_redirects = 0 
net.ipv4.conf.eth0.send_redirects = 0
net.ipv4.conf.default.accept_redirects = 0 
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.lo.accept_redirects = 0 
net.ipv4.conf.lo.send_redirects = 0

Por favor, observe que os arquivos / proc / sys / net / ipv4 / conf / ... são lidos apenas para usuários root. Você deve desativá-lo usando sua configuração de VPN. Por exemplo, no OpenSwan, você deve fazer:

Prompt> sudo vi /etc/sysctl.conf
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.all.send_redirects = 0

Você também pode usar

sudo sysctl stuff.you.want.to.change=newValue

Conforme sugerido pelos comentários para evitar a reinicialização