On Monday 21 August 2017 12:11:38 Christian Seiler wrote: > On 08/21/2017 05:03 PM, Gene Heskett wrote: > > On Monday 21 August 2017 09:08:11 Christian Seiler wrote: > >> 2. Can't add multiple IP addresses to the same interface and > >> (worse) even if multiple IP addresses are assigned to the > >> same interfaces it only shows the primary address > > > > I don't know as to how ifconfig sets it up, but its a piece of cake > > to edit /etc/network/interfaces to do that. If I bring in a new > > router, I uncomment this stanza in the interfaces file: > > ================ > > #auto eth0:1 > > > > # to access reset to 192.168.0.1 routers/switches on the 2nd cat5 > > port #iface eth0:1 inet static > > #address 192.168.0.3 > > #netmask 255.255.255.0 > > ============== > > giving me an address I can use to talk to and configure the new > > router. > > Yeah, that's the old way of doing this via an alias interface. I was > talking about the new-style way of doing so though. > > For example: > > auto eth0 > > iface eth0 inet static > address 192.168.0.1/24 > address 192.168.0.42/24 > address 10.5.6.7/8 > > This will work, and it will assign all IPs to the interface (the first > one being the primary and the source IP of outgoing packets where the > program doesn't explicitly bind anything). And "ip a" will show all > three addresses, but "ifconfig -a" will only show the first. > Ok, but then how do you differentiate between the addresses without the :1 [:2 etc] notation?
It doesn't seem right that is would bang all the assigned addresses with duplicate data. > Alias interfaes are kind of legacy, and while they still work, they do > have a couple of drawbacks: they aren't really an own interface > because they share options with the interface they are based on (which > can be confusing if you want to change interface options), there is no > way to automatically add a new IP to a given interface without probing > first which aliases have already been "used up", the alias namespace > is limited by both the max length of an interface name and the > limitation of the alias part itself. I haven't seen, or needed, one of the newer critters yet. But I'll be interested in the details when it does jump the fence into my domain. > But don't get me wrong: if it works for you with alias interfaces, I'm > certainly not going to tell you to change that - because those also do > work with the "ip" utility. The major issue I "ifconfig" has here is > that it doesn't see the additional IP addresses of interfaces added by > other tools - so that when you rely on ifconfig you _don't_ see the > actual entire network configuration of the system, but only a part of > it. So it's actually counter-productive when you're troubleshooting a > system. > > >> (2) is really bad, especially the part where it does not show > >> all of the IPs that were assigned by other tools, for example > > > > Huh? ifconfig doesn't even need a -a option to show me eth0:1 if ts > > configured and up. > > Yes, for alias interfaces it does. For the additional IPs added to the > interface itself it doesn't. > > >> NetworkManager, or Debian's own ifupdown via > >> /etc/network/interfaces. > > > > Please don't equate those two. > > I was talking about how these configure multiple IPs when you use > them. Both use the newer kernel interface that allows you to specify > multiple IPs on the same interface, while ifconfig uses the old > interface that assumes a single IP per interface. And I just used > the most prominent programs in Debian as examples for this, but all > other management tools I know of (conman, systemd-networkd, ...) > also use the newer interface. > > I really didn't want to discuss the merits or problems of each > individual software package. > > Regards, Thank you, Christian Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene>