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Old 07-02-2013, 07:10 AM   #1
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Registered: Jun 2011
Location: Vienna, Austria, Europe
Distribution: SuSE since 4.2
Posts: 4

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SuSE<->Cisco GRE Tunnel with ifcfg-file


I try to configure a GRE Tunnel with SuSE Linux to a Cisco router through NAT on my side. When I enter all commandy by hand, it works perfectly:
modprobe ip_gre
iptunnel add tun0 mode gre local remote ttl 225
ifconfig tun0
ifconfig tun0 up
ifconfig tun0 pointopoint
route add default gw
But when I try to do that with /etc/sysconfic/network/ifcfg-tun0, I only get non-working tunnels. No error message; just no traffic through the tunnel.
Can somebody help me please? Thanks!!!
Old 07-02-2013, 11:52 AM   #2
LQ Newbie
Registered: Jun 2011
Location: Vienna, Austria, Europe
Distribution: SuSE since 4.2
Posts: 4

Original Poster
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When I add
to the ifcfg file, it works.

However, when I shrink the Prefix down to /31 it produces a strange tunnel configuration with local and remote endpoint being the same IP address.
tun0      Link encap:UNSPEC  HWaddr C0-A8-01-02-97-BF-48-7E-00-00-00-00-00-00-00-00
          inet addr:  P-t-P:  Mask:
          UP POINTOPOINT RUNNING NOARP  MTU:1476  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
But it works, nevertheless. Obviously the `ifupī script on SuSE 11.2 can't handle /31 netmasks properly.


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