VPN - leitura curta (-1): 'Mensagem muito longa'

Question

Então, estou tentando usar minha VPN em um hotel wi-fi, onde estou de férias, mas, por algum motivo, tenho esse problema chato. Quando me conecto à minha VPN em alguns segundos, ela é interrompida e o syslog é exibido:

Jun 14 20:51:14 botev-ThinkPad-T440 NetworkManager[845]: <info> Starting VPN service 'pptp'...
Jun 14 20:51:14 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN service 'pptp' started (org.freedesktop.NetworkManager.pptp), PID 9778
Jun 14 20:51:14 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN service 'pptp' appeared; activating connections
Jun 14 20:51:14 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN plugin state changed: init (1)
Jun 14 20:51:14 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN plugin state changed: starting (3)
Jun 14 20:51:14 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN connection 'UCL CS VPN' (Connect) reply received.
Jun 14 20:51:14 botev-ThinkPad-T440 pppd[9783]: Plugin /usr/lib/pppd/2.4.5/nm-pptp-pppd-plugin.so loaded.
Jun 14 20:51:14 botev-ThinkPad-T440 pppd[9783]: pppd 2.4.5 started by root, uid 0
Jun 14 20:51:14 botev-ThinkPad-T440 pppd[9783]: Using interface ppp0
Jun 14 20:51:14 botev-ThinkPad-T440 pppd[9783]: Connect: ppp0 <--> /dev/pts/9
Jun 14 20:51:14 botev-ThinkPad-T440 pptp[9787]: nm-pptp-service-9778 log[main:pptp.c:314]: The synchronous pptp option is NOT activated
Jun 14 20:51:14 botev-ThinkPad-T440 NetworkManager[845]:    SCPlugin-Ifupdown: devices added (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
Jun 14 20:51:14 botev-ThinkPad-T440 NetworkManager[845]:    SCPlugin-Ifupdown: device added (path: /sys/devices/virtual/net/ppp0, iface: ppp0): no ifupdown configuration found.
Jun 14 20:51:14 botev-ThinkPad-T440 NetworkManager[845]: <warn> /sys/devices/virtual/net/ppp0: couldn't determine device driver; ignoring...
Jun 14 20:51:14 botev-ThinkPad-T440 kernel: [ 5763.841477] init: network-interface (ppp0) pre-start process (9794) terminated with status 1
Jun 14 20:51:14 botev-ThinkPad-T440 kernel: [ 5763.846659] init: network-interface (ppp0) post-stop process (9802) terminated with status 1
Jun 14 20:51:14 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 1 'Start-Control-Connection-Request'
Jun 14 20:51:14 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 log[ctrlp_disp:pptp_ctrl.c:739]: Received Start Control Connection Reply
Jun 14 20:51:14 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 log[ctrlp_disp:pptp_ctrl.c:773]: Client connection established.
Jun 14 20:51:15 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 7 'Outgoing-Call-Request'
Jun 14 20:51:15 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 log[ctrlp_disp:pptp_ctrl.c:858]: Received Outgoing Call Reply.
Jun 14 20:51:15 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 log[ctrlp_disp:pptp_ctrl.c:897]: Outgoing call established (call ID 0, peer's call ID 1661).
Jun 14 20:51:15 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 log[ctrlp_disp:pptp_ctrl.c:950]: PPTP_SET_LINK_INFO received from peer_callid 56205
Jun 14 20:51:15 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 log[ctrlp_disp:pptp_ctrl.c:953]:   send_accm is 00000000, recv_accm is FFFFFFFF
Jun 14 20:51:15 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 warn[ctrlp_disp:pptp_ctrl.c:956]: Non-zero Async Control Character Maps are not supported!
Jun 14 20:51:15 botev-ThinkPad-T440 pppd[9783]: CHAP authentication succeeded
Jun 14 20:51:15 botev-ThinkPad-T440 pppd[9783]: MPPE 128-bit stateless compression enabled
Jun 14 20:51:17 botev-ThinkPad-T440 pppd[9783]: local  IP address 128.16.114.3
Jun 14 20:51:17 botev-ThinkPad-T440 pppd[9783]: remote IP address 128.16.114.1
Jun 14 20:51:17 botev-ThinkPad-T440 pppd[9783]: primary   DNS address 128.16.6.8
Jun 14 20:51:17 botev-ThinkPad-T440 pppd[9783]: secondary DNS address 128.16.5.31
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN connection 'UCL CS VPN' (IP4 Config Get) reply received from old-style plugin.
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN Gateway: 128.16.11.245
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info> Tunnel Device: ppp0
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info> IPv4 configuration:
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info>   Internal Address: 128.16.114.3
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info>   Internal Prefix: 32
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info>   Internal Point-to-Point Address: 128.16.114.1
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info>   Maximum Segment Size (MSS): 0
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info>   Forbid Default Route: no
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info>   Internal DNS: 128.16.6.8
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info>   Internal DNS: 128.16.5.31
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info>   DNS Domain: '(none)'
Jun 14 20:51:17 botev-ThinkPad-T440 NetworkManager[845]: <info> No IPv6 configuration
Jun 14 20:51:18 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN connection 'UCL CS VPN' (IP Config Get) complete.
Jun 14 20:51:18 botev-ThinkPad-T440 NetworkManager[845]: <info> Policy set 'UCL CS VPN' (ppp0) as default for IPv4 routing and DNS.
Jun 14 20:51:18 botev-ThinkPad-T440 NetworkManager[845]: <info> Writing DNS information to /sbin/resolvconf
Jun 14 20:51:18 botev-ThinkPad-T440 dnsmasq[3602]: setting upstream servers from DBus
Jun 14 20:51:18 botev-ThinkPad-T440 dnsmasq[3602]: using nameserver 128.16.5.31#53
Jun 14 20:51:18 botev-ThinkPad-T440 dnsmasq[3602]: using nameserver 128.16.6.8#53
Jun 14 20:51:18 botev-ThinkPad-T440 dbus[525]: [system] Activating service name='org.freedesktop.nm_dispatcher' (using servicehelper)
Jun 14 20:51:18 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN plugin state changed: started (4)
Jun 14 20:51:18 botev-ThinkPad-T440 dbus[525]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
Jun 14 20:51:20 botev-ThinkPad-T440 pptp[9787]: nm-pptp-service-9778 warn[decaps_gre:pptp_gre.c:331]: short read (-1): Message too long
Jun 14 20:51:20 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 log[callmgr_main:pptp_callmgr.c:234]: Closing connection (unhandled)
Jun 14 20:51:20 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 12 'Call-Clear-Request'
Jun 14 20:51:20 botev-ThinkPad-T440 pptp[9807]: nm-pptp-service-9778 log[call_callback:pptp_callmgr.c:79]: Closing connection (call state)
Jun 14 20:51:20 botev-ThinkPad-T440 pppd[9783]: Modem hangup
Jun 14 20:51:20 botev-ThinkPad-T440 pppd[9783]: Connect time 0.1 minutes.
Jun 14 20:51:20 botev-ThinkPad-T440 pppd[9783]: Sent 7680 bytes, received 13570 bytes.
Jun 14 20:51:20 botev-ThinkPad-T440 pppd[9783]: MPPE disabled
Jun 14 20:51:20 botev-ThinkPad-T440 pppd[9783]: Connection terminated.
Jun 14 20:51:20 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN plugin state changed: stopping (5)
Jun 14 20:51:20 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN plugin state changed: stopped (6)
Jun 14 20:51:20 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN plugin state change reason: 0
Jun 14 20:51:20 botev-ThinkPad-T440 avahi-daemon[581]: Withdrawing workstation service for ppp0.
Jun 14 20:51:20 botev-ThinkPad-T440 avahi-daemon[581]: Withdrawing address record for 172.17.31.180 on wlan0.
Jun 14 20:51:20 botev-ThinkPad-T440 avahi-daemon[581]: Leaving mDNS multicast group on interface wlan0.IPv4 with address 172.17.31.180.
Jun 14 20:51:20 botev-ThinkPad-T440 avahi-daemon[581]: Interface wlan0.IPv4 no longer relevant for mDNS.
Jun 14 20:51:20 botev-ThinkPad-T440 avahi-daemon[581]: Joining mDNS multicast group on interface wlan0.IPv4 with address 172.17.31.180.
Jun 14 20:51:20 botev-ThinkPad-T440 avahi-daemon[581]: New relevant interface wlan0.IPv4 for mDNS.
Jun 14 20:51:20 botev-ThinkPad-T440 avahi-daemon[581]: Registering new address record for 172.17.31.180 on wlan0.IPv4.
Jun 14 20:51:19 botev-ThinkPad-T440 whoopsie[1103]: message repeated 6 times: [ online]
Jun 14 20:51:20 botev-ThinkPad-T440 whoopsie[1103]: offline
Jun 14 20:51:21 botev-ThinkPad-T440 pppd[9783]: Exit.
Jun 14 20:51:21 botev-ThinkPad-T440 NetworkManager[845]: <info> Policy set 'Hotel Broadband' (wlan0) as default for IPv4 routing and DNS.
Jun 14 20:51:21 botev-ThinkPad-T440 NetworkManager[845]: <info> Writing DNS information to /sbin/resolvconf
Jun 14 20:51:21 botev-ThinkPad-T440 dnsmasq[3602]: setting upstream servers from DBus
Jun 14 20:51:21 botev-ThinkPad-T440 dnsmasq[3602]: using nameserver 172.17.31.1#53
Jun 14 20:51:21 botev-ThinkPad-T440 NetworkManager[845]: <warn> error disconnecting VPN: Could not process the request because no VPN connection was active.
Jun 14 20:51:21 botev-ThinkPad-T440 NetworkManager[845]: <warn> (14) failed to find interface name for index
Jun 14 20:51:21 botev-ThinkPad-T440 NetworkManager[845]: nm_system_iface_flush_routes: assertion 'iface != NULL' failed
Jun 14 20:51:21 botev-ThinkPad-T440 NetworkManager[845]: <warn> (14) failed to find interface name for index
Jun 14 20:51:21 botev-ThinkPad-T440 NetworkManager[845]:    SCPlugin-Ifupdown: devices removed (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
Jun 14 20:51:20 botev-ThinkPad-T440 whoopsie[1103]: offline
Jun 14 20:51:22 botev-ThinkPad-T440 whoopsie[1103]: online
Jun 14 20:51:24 botev-ThinkPad-T440 ntpdate[9867]: adjust time server 91.189.89.199 offset -0.003853 sec
Jun 14 20:51:27 botev-ThinkPad-T440 NetworkManager[845]: <info> VPN service 'pptp' disappeared

Agora, seguindo um problema muito similar aqui e aqui Eu tentei mudar o MTU para o meu wlan0 e ppp0 também. Por alguma razão, o wlan0 foi limitado a 2304, se eu tentar sudo ifconfig wlan0 mtu X para algo maior, recebo a mensagem de erro SIOCSIFMTU: Invalid argument . Para o ppp0, no entanto, consegui definir quase tudo (tentei com 30000 e funciona). No entanto, isso não ajudou a resolver o problema. Então, aqui estou me perguntando se há alguma mudança para mim?

Estou usando o Ubuntu 14.04 com o kernel 3.17.

    

Answer 1

Ok, então depois de mais algumas escavações e muitos experimentos, na verdade eu tenho que baixar o MTU de wlan0, ao invés de aumentá-lo. A razão, até onde eu entendi e por favor, corrija se eu estiver errado, é que provavelmente um dos roteadores ou um switch no caminho está tendo um MTU mais baixo também, assim, embora ele envie os pacotes corretamente, meu palpite é que o O servidor VPN vê apenas o MTU dos pacotes de VPN e responde com esse MTU. Quando eles atingem este roteador, ele simplesmente desiste, porque o pacote de entrada é muito grande. Mais uma vez, essa é a minha hipótese sobre o assunto. Quanto a baixá-lo, não posso dizer exatamente. Eu fiz primeiro 1412, do que 1400 e 1200, no final, foi mais estável em 1000, então eu fico com isso. Se isso acontecer, experimente um pouco com isso.

    

Answer 2

Eu tive esse problema há alguns minutos e foi assim que resolvi:

sudo ifconfig ppp0 mtu 1300

Este comando mudou o tamanho da MTU para a conexão ppp0 apenas nesta sessão.

Se você quiser usar permanentemente essas configurações para sua conexão, crie um novo arquivo no diretório /etc/network/if-up.d/ Exemplo:

 sudo vi /etc/network/if-up.d/ppp0-mtu

com o conteúdo:

#!/bin/sh

if [ "$IFACE" = "ppp0" ]; then
    sudo ifconfig ppp0 mtu 1300
fi

torne este arquivo executável e verifique sua conexão VPN agora

sudo chmod a+x /etc/network/if-up.d/ppp0-mtu

    

Answer 3

Você pode usar o traceroute para descobrir o menor mtu no caminho para o host. o comando é: traceroute <host> --mtu

No meu caso, o MTU inferior era 1280, então eu usei 1200 para fazer o vpn na configuração do roteador.