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don quixada
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PostPosted: Fri Jan 15, 2016 1:02 pm    Post subject: Internet Not Reachable (intermittantly) Reply with quote

Hey guys, I'm getting a strange problem where occasionally I cannot seem to access anything outside my network from my Gentoo box. I can ping local devices and the router but no websites resolve and I cannot ping my dns servers either. This problem only happens occasionally, otherwise everything works as normal. And when the problem does occur, I restart the net.enp3s0 service but nothing changes. It's not my firewall either. Any ideas on how to troubleshoot when it occurs? Thanks.

dq
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massimo
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PostPosted: Fri Jan 15, 2016 5:08 pm    Post subject: Reply with quote

Are you able to ping any other IP address on the Internet? Do you use your provider's DNS servers? If they fail from time to time you could try use different ones.
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don quixada
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PostPosted: Fri Jan 15, 2016 6:14 pm    Post subject: Reply with quote

I use OpenDNS's servers. They didn't return any packets when pinging. I didn't try any other IPs but I suspect it would be the same result. Oh, and the other devices on WiFi etc. connect to the internet without any issues...

Also, when it does work again it suddenly starts working regardless of what I have done. I'm not sure if there's some Cron-job that is doing something weird.

I also have experiencing some strange system clock issues. I usually update my system clock using ntpd but when the internet is down obviously it doesn't work. As a result, when not connected the time is off by about 20 mins. I'm not sure why it would be so different when it is not connected to the internet-- maybe it's an unrelated thing but at this point I'm seeing if anything is the culprit...

dq
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massimo
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PostPosted: Fri Jan 15, 2016 10:01 pm    Post subject: Reply with quote

Anything in the logs/dmesg regarding the network port's status? Change the network cable and check if it still happens.
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don quixada
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PostPosted: Sat Jan 16, 2016 5:51 am    Post subject: Reply with quote

The network still works because I can connect to local devices including the router. The only thing that I see indicating anything that is wrong is ddclient cannot connect which makes sense.

The only other thing that I see in the log that is strange is my Chromecast ip-address. I'm not sure if it's normal behavior but it looks something like this:
Code:
Jan 14 15:59:06 localhost kernel: Shorewall:net2fw:REJECT:IN=enp3s0 OUT= MAC=60:a4:4c:64:1a:90:54:60:09:f4:f1:5a:08:00 SRC=192.168.2.179 DST=192.168.2.151 LEN=543 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=53488 DPT=39566 LEN=523
Jan 14 15:59:07 localhost kernel: Shorewall:net2fw:REJECT:IN=enp3s0 OUT= MAC=60:a4:4c:64:1a:90:54:60:09:f4:f1:5a:08:00 SRC=192.168.2.179 DST=192.168.2.151 LEN=543 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=39379 DPT=39566 LEN=523
Jan 14 15:59:08 localhost kernel: Shorewall:net2fw:REJECT:IN=enp3s0 OUT= MAC=60:a4:4c:64:1a:90:54:60:09:f4:f1:5a:08:00 SRC=192.168.2.179 DST=192.168.2.151 LEN=543 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=41845 DPT=39566 LEN=523
Jan 14 15:59:45 localhost kernel: Shorewall:net2fw:REJECT:IN=enp3s0 OUT= MAC=60:a4:4c:64:1a:90:54:60:09:f4:f1:5a:08:00 SRC=192.168.2.179 DST=192.168.2.151 LEN=543 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=54390 DPT=35798 LEN=523
Jan 14 15:59:46 localhost kernel: Shorewall:net2fw:REJECT:IN=enp3s0 OUT= MAC=60:a4:4c:64:1a:90:54:60:09:f4:f1:5a:08:00 SRC=192.168.2.179 DST=192.168.2.151 LEN=543 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=35054 DPT=35798 LEN=523
Jan 14 15:59:47 localhost kernel: Shorewall:net2fw:REJECT:IN=enp3s0 OUT= MAC=60:a4:4c:64:1a:90:54:60:09:f4:f1:5a:08:00 SRC=192.168.2.179 DST=192.168.2.151 LEN=543 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=37229 DPT=35798 LEN=523
Jan 14 15:59:48 localhost kernel: Shorewall:net2fw:REJECT:IN=enp3s0 OUT= MAC=60:a4:4c:64:1a:90:54:60:09:f4:f1:5a:08:00 SRC=192.168.2.179 DST=192.168.2.151 LEN=543 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=58958 DPT=35798 LEN=523

Not sure what that's all about...

dq
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massimo
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PostPosted: Sat Jan 16, 2016 7:16 am    Post subject: Reply with quote

When it fails can you do a traceroute to any public IP address.
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don quixada
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PostPosted: Sat Jan 16, 2016 5:29 pm    Post subject: Reply with quote

Ok, well I'll try it when it happens again...
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GOS
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PostPosted: Sun Jan 24, 2016 9:56 am    Post subject: Reply with quote

Had nearly the same problem some time ago. After resume from standby I had the same issue you describe. I mentioned in this context that my machine was not abled to look into the routing table. So it could be that "route" shows you the routing table not immediately but after a long time instead.

I solved the problem by unloading and reloading the module of my network card after resume by "modprobe -r ..." "modprobe ...".

regards GOS

PS: I use NetworkManager. I do not know if this has any impact.
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NeddySeagoon
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PostPosted: Sun Jan 24, 2016 10:35 am    Post subject: Reply with quote

don quixada,

Code:
Jan 14 15:59:06 localhost kernel: Shorewall:net2fw:REJECT:IN=enp3s0 OUT= MAC=60:a4:4c:64:1a:90:54:60:09:f4:f1:5a:08:00 \
SRC=192.168.2.179 DST=192.168.2.151 \
LEN=543 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=53488 DPT=39566 LEN=523


That says that something from the outside (net) is trying to connect to the firewall (fw).
The source of that something from the outside is 192.168.2.179.

However, 192.168.0.0/16 is a not routable IP range, therefore your ISP should not be sending it to you, or anybody else.
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NeddySeagoon

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those that do backups
those that have never had a hard drive fail.
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