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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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No route to host until I ping and then it works fine? (lemmy.nz)

submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/[email protected]

19 comments fedilink hide all child comments

Probably should find a linux networking specific community for this one..

I have a strange issue that feels very familiar, like I've fixed it before, but I can't remember how.

I try to rtsp to security cam:

ffplay rtsp://user:[email protected]:554/h264Preview_01_main

And I get a no route:

Connection to tcp://192.168.19.137:554?timeout=0 failed: No route to host

rtsp://user:[email protected]:554/h264Preview_01_main: No route to host

Strange, I'm in the same subnet 192.168.19.129/24, and it worked a few days ago.

Check ping:

ping 192.168.19.137

PING 192.168.19.137 (192.168.19.137) 56(84) bytes of data.

64 bytes from 192.168.19.137: icmp_seq=1 ttl=64 time=5.69 ms

Of course.. So I run the command again;

ffplay rtsp://user:[email protected]:554/h264Preview_01_main

And now it works.

I could bandaid by crontabbing a ping every hour or something, but I would really like to know why I'm getting a 'no route' until I ping.

My routing table is pretty basic:

default via 192.168.19.1 dev enp4s0 proto dhcp src 192.168.19.129 metric 100

default via 192.168.19.1 dev enp4s0 proto dhcp src 192.168.19.129 metric 1002

172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown

172.18.0.0/16 dev br-68c1e0344e27 proto kernel scope link src 172.18.0.1 linkdown

192.168.19.0/24 dev enp4s0 proto dhcp scope link src 192.168.19.129 metric 1002

192.168.19.1 dev enp4s0 proto dhcp scope link src 192.168.19.129 metric 1024

And I don't think I have any rules in firewall for LAN.

Any ideas?

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[–] [email protected] 5 points 1 year ago

Is there an IPSec tunel in the mix? Often, IPSec Phase2 goes down when idle, while Phase1 stays up. Upon traffic, Phase2 is brought up again, with a delay.

I usually work around this with a crontab on one of the remote servers that sends a single ping packet every minute to a local server, and pipe any output to /dev/null.