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On Thu, Feb 16, 2023 at 9:08 AM John Covici <covici@××××××××××.com> wrote: |
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> |
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> hmmm, but what should I use for the source ip, I only assign those |
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> when I bring the interface up when I start the interface -- I have |
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> something like this: |
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> [Unit] |
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> Description=Network Connectivity for %i |
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> ... |
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> So, before I run this, I don't think the card has any ip address, does |
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> it? |
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So, "cards" don't have an IP address. The kernel assigns an IP |
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address to an interface, which is entirely a software construct. It |
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happens to be a software construct that the network console feature |
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largely ignores anyway. |
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I didn't go reading the source code, but I'm guessing it is just |
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constructing raw UDP packets and it will happily set the IP to |
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whatever you want it to be. After all, it is just a field on the |
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packet. |
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So you can make the source IP whatever you want it to be. Just expect |
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the packets to show up with the IP you set on them. There is no |
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connection, so the IP doesn't need to be reachable by anything else. |
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You could stick literally anything in there as long as some firewall |
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isn't going to object and drop the packet. The destination IP matters |
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because that is where it is going to go, and the interface matters |
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because if it gets sent out on the wrong interface then obviously it |
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won't make it there. |
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I have no idea if the netconsole packets get seen by netfilter, but if |
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this is on some kind of router that might be something you need to |
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check, because if netfilter is configured to drop unassociated UDP |
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from the firewall to the LAN that could be an issue. However, it is |
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possible this just bypasses netfilter entirely. |
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If you have the dynamic netconsole option enabled you could have a |
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script update the settings after your network is up to set the source |
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IP to the one assigned by DHCP and make sure it is on the right |
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interface. As you point out though at boot time the interface won't |
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have an IP. It won't even be "up," not that this is likely to bother |
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the kernel. |
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-- |
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Rich |
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