# dhcpcd crashes router periodically [SOLVED]

## alootiki

I use wpa_supplicant with dhcpcd to connect to my home router, which uses WPA2. (I actually started with Wicd, which was way too buggy, then switched to NetworkManager, which was excellent but rather slow to start and pulled a bit too much Gnome for my taste, and ended up on wpa_supplicant)

It connects fine, but I encountered a strange issue: the router drops all connections every few minutes or so, after which it takes about a minute to get back on the network. It appears the router was flooded with dhcp requests. My computer's systemd journal is also spammed with notifications from dhcpcd.

It looks like this:

```

Sep 04 20:36:15 localhost dhcpcd[3892]: wlp2s0: Router Advertisement from fe80::5e57:1aff:fea1:e091

Sep 04 20:36:18 localhost dhcpcd[3892]: wlp2s0: Router Advertisement from fe80::5e57:1aff:fea1:e091

Sep 04 20:36:21 localhost dhcpcd[3892]: wlp2s0: fe80::5e57:1aff:fea1:e091: expired option 25

Sep 04 20:36:21 localhost dhcpcd[3892]: wlp2s0: fe80::5e57:1aff:fea1:e091: expired option 25

Sep 04 20:36:21 localhost dhcpcd[3892]: wlp2s0: Router Advertisement from fe80::5e57:1aff:fea1:e091

Sep 04 20:36:24 localhost dhcpcd[3892]: wlp2s0: Router Advertisement from fe80::5e57:1aff:fea1:e091

Sep 04 20:36:27 localhost dhcpcd[3892]: wlp2s0: fe80::5e57:1aff:fea1:e091: expired option 25

Sep 04 20:36:27 localhost dhcpcd[3892]: wlp2s0: fe80::5e57:1aff:fea1:e091: expired option 25

Sep 04 20:36:27 localhost dhcpcd[3892]: wlp2s0: Router Advertisement from fe80::5e57:1aff:fea1:e091

Sep 04 20:36:30 localhost dhcpcd[3892]: wlp2s0: Router Advertisement from fe80::5e57:1aff:fea1:e091

Sep 04 20:36:33 localhost dhcpcd[3892]: wlp2s0: Router Advertisement from fe80::5e57:1aff:fea1:e091

Sep 04 20:36:36 localhost dhcpcd[3892]: wlp2s0: fe80::5e57:1aff:fea1:e091: expired option 25

Sep 04 20:36:36 localhost dhcpcd[3892]: wlp2s0: fe80::5e57:1aff:fea1:e091: expired option 25

Sep 04 20:36:36 localhost dhcpcd[3892]: wlp2s0: Router Advertisement from fe80::5e57:1aff:fea1:e091

Sep 04 20:36:39 localhost dhcpcd[3892]: wlp2s0: Router Advertisement from fe80::5e57:1aff:fea1:e091

Sep 04 20:36:42 localhost dhcpcd[3892]: wlp2s0: fe80::5e57:1aff:fea1:e091: expired option 25

Sep 04 20:36:42 localhost dhcpcd[3892]: wlp2s0: fe80::5e57:1aff:fea1:e091: expired option 25

```

This is only the log for the past 30 seconds or so.

I am fairly sure that dhcpcd is the root cause of this, since if I kill dhcpcd and only connect with wpa_supplicant no more crashes occur. I have not edited my dhcpcd.conf from the default. The command systemd uses to start dhcpcd is 

```
/sbin/dhcpcd -q --nobackground wlp2s0
```

I don't know if this is normal behavior of dhcpcd or a documented bug. I couldn't find any other reports of this issue.Last edited by alootiki on Sun Sep 07, 2014 5:23 pm; edited 1 time in total

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## Hu

If your router is crashing, that is a router bug.  Nothing that dhcpcd puts on the network, no matter how ill-formed, can crash a non-buggy peer.  All the quoted log messages are related to IPv6.  Does it help if you configure the router to use IPv4 only?

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## UberLord

Fix your router so that the RA option expiry (looks like 3 seconds) is greater than the RA refresh time.

Also try upgrading your dhcpcd, never versions from around 6.3 reduced needless log spam.

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## alootiki

Thanks for the advice. It's probably worth mentioning that I set global ~amd64 in portage.

I certainly can't rule out the possibility of a router bug, but it is strange that only my laptop seems to break things while connecting. The rest of the family (on Windows 7/8 or iSomething) seems to have no problem. I haven't gotten the hang of configuring the router, but I will try that.

Apparently there have been reports of problems with IPv6 in dhcpcd >= 6.4.2 according to portage news (that's what I get for ignoring portage's news notifications). I am trying the fix suggested in the message, and will report back with results. If that doesn't work and I can't find anything else odd on my laptop in the next few days, I'll chalk it up to a router bug and mark this solved.

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## UberLord

 *alootiki wrote:*   

> Thanks for the advice. It's probably worth mentioning that I set global ~amd64 in portage.
> 
> I certainly can't rule out the possibility of a router bug, but it is strange that only my laptop seems to break things while connecting. The rest of the family (on Windows 7/8 or iSomething) seems to have no problem. I haven't gotten the hang of configuring the router, but I will try that.
> 
> Apparently there have been reports of problems with IPv6 in dhcpcd >= 6.4.2 according to portage news (that's what I get for ignoring portage's news notifications). I am trying the fix suggested in the message, and will report back with results. If that doesn't work and I can't find anything else odd on my laptop in the next few days, I'll chalk it up to a router bug and mark this solved.

 

No that was portage warning you about a change in the default Ipv6 autoconf address that would be assigned.

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## alootiki

Whatever the problem was, it seems to be resolved. It may actually have been a router problem, since I think my dad changed some settings while I was fiddling with my laptop. FWIW, ping no longer works for external sites (e.g. google.com), only ping6, but that doesn't really matter to me.

Thank you all for your help.

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## UberLord

 *alootiki wrote:*   

> Whatever the problem was, it seems to be resolved. It may actually have been a router problem, since I think my dad changed some settings while I was fiddling with my laptop. FWIW, ping no longer works for external sites (e.g. google.com), only ping6, but that doesn't really matter to me.
> 
> Thank you all for your help.

 

He might be blocking ICMP at the firewall. This is generally a bad thing (some ICMP packets are good, such as ping) but as you point out, not fatal.

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