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daggerfall

Member

Registered: 2015-04-09

Posts: 4

System full hang on xl2tpd connection

Hi there. I really don't know reason of hard system hangs(only power button helps), connection work stable until the moment of system update and my ISP local network collapse and update (new ip range and gateway, maybe something else)
In /etc/ppp I have scripts what adding routings for ISP resources and for successfull creation of vpn tunnel, local ISP gateway was static in there and first what I was thinking - is the reason, but I started from zero configs, and for xl2tpd too, added just one routing to ISP L2TP server 85.21.0.0 (subnet with that server) (connection will not create without it, and xl2tpd writes totally nonsense to log something like: can't handle param 46,106), right after CHAP was successfull and IP received - bang, hang. Nothing writed in log after that. System was clean (before those hangs) and up to date
Please help me with that, maybe kernel bug?
Sorry for my english.

options.xl2tpd

lcp-echo-interval 10
lcp-echo-failure 2
name login
remotename l2tp
ipparam isp
connect /bin/true
mru 1500
mtu 1460
nodeflate
nobsdcomp
persist
maxfail 0
nopcomp
noaccomp
noauth

xl2tpd.conf

[global]
access control = yes
auth file = /etc/ppp/chap-secrets

[lac isp]
lns = 85.21.x.x
redial = yes
redial timeout = 15
require chap = yes
require authentication = no
name = login
ppp debug = no
pppoptfile = /etc/ppp/options.xl2tpd
require pap = no
autodial = yes
tx bps = 100000000

Last edited by daggerfall (2015-04-09 02:28:51)

daggerfall

Member

Registered: 2015-04-09

Posts: 4

Re: System full hang on xl2tpd connection

I think I know what happens, something like what described here
http://forums.openl2tp.org/viewtopic.ph … 5c9595acb9
Right after start xl2tpd system adding wrong route whitch lead to hang (is some way to avoid hang problem because route mismatch? it isnt normally I think!)

route add remote-tunnel-ip dev ppp0
which leads to cpu lockup I described earlier.

Strictly speaking, it is not openl2tp problem, but kernel ppp/routing subsystem one, but it appears only with kernel IP-over-IP tunnel implementations (so, really, only with openl2tp).

So, there is 2 problems:
1)wrong routing leads to cpu lockup - i don't think that it's normal situation when ANY routing mismatch can cause complete system hang
2)the wrong route is added by default and pppd has no option to disable it

The only workaround I found is to fix routing in ip-up scripts. It's ok solution for home use with small network load, but it is unacceptable for big network loads because system can hang before executing of userspace ip-up scripts.

xl2tpd have option nodefaultroute, but I even don't know working it or not, system hangs with these too

Last edited by daggerfall (2015-04-09 13:52:13)