[Bug 1227326] New: Machine running dnsmasq no longer answers DHCP requests
https://bugzilla.suse.com/show_bug.cgi?id=1227326 Bug ID: 1227326 Summary: Machine running dnsmasq no longer answers DHCP requests Classification: openSUSE Product: openSUSE Tumbleweed Version: Current Hardware: x86-64 OS: openSUSE Tumbleweed Status: NEW Severity: Major Priority: P5 - None Component: Kernel:Networking Assignee: kernel-bugs@suse.de Reporter: rainer.klute@gmx.de QA Contact: qa-bugs@suse.de Target Milestone: --- Found By: --- Blocker: --- After a recent update of my server, dnsmasq no longer answers DHCP requests. Or rather, dnsmasq seems to produce answers, but clients don’t receive them. I used wireshark on the server as well as on one of the clients to have a closer look. On the server, wireshark shows incoming DHCPDISCOVER and outgoing DHCPOFFER messages as should be. However, on the client, wireshark only shows the outgoing DHCPDISCOVER messages but no corresponding incoming DHCPOFFER messages. So the packets seem to get lost between wireshark logging them and the packets actually hitting the wire (or rather the WiFi antenna). This problem affects all clients, including Android smartphones, so the problem is clearly on the server side. Dnsmasq hasn’t been updated since months, so it likely isn’t the culprit. I didn’t change any relevant system configuration, e.g. firewall settings. I observed this behavior under kernel 6.9.7. Reverting back to 6.9.6 didn’t help, however. By the way, dnsmasq answers DNS queries still just fine. Any ideas? What else could I try? -- You are receiving this mail because: You are on the CC list for the bug.
https://bugzilla.suse.com/show_bug.cgi?id=1227326 https://bugzilla.suse.com/show_bug.cgi?id=1227326#c1 --- Comment #1 from Rainer Klute <rainer.klute@gmx.de> --- Is there no one here to take over? Not even for a rejection? -- You are receiving this mail because: You are on the CC list for the bug.
https://bugzilla.suse.com/show_bug.cgi?id=1227326 https://bugzilla.suse.com/show_bug.cgi?id=1227326#c2 --- Comment #2 from Rainer Klute <rainer.klute@gmx.de> --- Meanwhile, I updated all Linux machines to kernel version 6.9.9, which didn’t help. However, I also reactived an old notebook, updated it to the most recent Tumbleweed version, and – lo and behold – it DOES receive DHCP messages from the DHCP server (dnsmasq) and gets a proper network configuration! All other clients in my network don’t, which are a few Linux machines as well as Android phones. -- You are receiving this mail because: You are on the CC list for the bug.
https://bugzilla.suse.com/show_bug.cgi?id=1227326 https://bugzilla.suse.com/show_bug.cgi?id=1227326#c3 --- Comment #3 from Rainer Klute <rainer.klute@gmx.de> --- Next insight: To rule out possible influences from possibly different system configurations, I used the Tumbleweed network installer as a minimal and standardised DHCP client on two different machines. One of these machines was the reactivated notebook mentioned above, which receives DHCP responses when running the installed Linux system. In both cases, the DHCP client received no network configuration via DHCP. This really is a mystery! But I believe we can conclude that it is a server issue, especially since also Android clients are affected. What else can I do to investigate this further? (Assuming someone is reading this at all …) -- You are receiving this mail because: You are on the CC list for the bug.
https://bugzilla.suse.com/show_bug.cgi?id=1227326 https://bugzilla.suse.com/show_bug.cgi?id=1227326#c4 --- Comment #4 from Rainer Klute <rainer.klute@gmx.de> --- I have now tried the ISC DHCP server instead of dnsmasq, which works perfectly. So the problem seems to be in dnsmasq itself or rather in the interaction between dnsmasq and something else. After all, dnsmasq 2.90 has been installed unchanged for months, but the problem has only occurred recently. The problem may have been caused by the update of some other system component. In any case, I would prefer to stick with dnsmasq, not least because of the integrated DDNS functionality, which means that clients can be found in the network under the names they specified via DHCP. -- You are receiving this mail because: You are on the CC list for the bug.
https://bugzilla.suse.com/show_bug.cgi?id=1227326 https://bugzilla.suse.com/show_bug.cgi?id=1227326#c5 --- Comment #5 from Rainer Klute <rainer.klute@gmx.de> --- PING – anyone listening? -- You are receiving this mail because: You are on the CC list for the bug.
https://bugzilla.suse.com/show_bug.cgi?id=1227326 https://bugzilla.suse.com/show_bug.cgi?id=1227326#c7 --- Comment #7 from Rainer Klute <rainer.klute@gmx.de> --- Good idea! I’ll have to find some hardware and do the setup and the tests, so this will take some time … Apparmor or SELinux are not involved. -- You are receiving this mail because: You are on the CC list for the bug.
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