Skip to main content

linux - TCP listen on any IPv6 in a block on Debian

I have a /64 block of IPv6 addresses, and I'd like to be able to start a TCP server listening on any one of them. Currently I can bind to any static IP address, but not any others. If I try to bind to an address not statically routed (by the way, I'm not sure if I'm using the right terms), I get an error message, "bind: cannot assign requested address".



Here's from ifconfig:



eth0      Link encap:Ethernet  HWaddr 56:00:00:60:af:c6
          inet addr:104.238.191.172  Bcast:104.238.191.255  Mask:255.255.254.0
          inet6 addr: fe80::5400:ff:fe60:afc6/64 Scope:Link
          inet6 addr: 2001:19f0:6801:187:5400:ff:fe60:afc6/64 Scope:Global
          inet6 addr: 2001:19f0:6801:187:ea1e:eb99:13ae:d49a/128 Scope:Global

          UP BROADCAST RUNNING ALLMULTI MULTICAST  MTU:1500  Metric:1
          RX packets:1526389 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1622562 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:280302410 (267.3 MiB)  TX bytes:266740313 (254.3 MiB)


If I try to bind to e.g. 2001:19f0:6801:187:a:b:c:d, it fails with "bind: cannot assign requested address". But if I do ip -6 addr add dev eth0 2001:19f0:6801:187:a:b:c:d, then I'm able to start the server listening on that IP address.



How can I configure Linux so that I can listen on any 2001:19f0:6801:187::/64 address? That is, I want to bind to some specific IP address without having to ip addr add it first.




Or should I just have my server ip addr add an address before binding, then maybe ip addr del it when I'm done?



Addendum: In case my problem isn't clear, I've already gotten far enough that the whole prefix is getting routed to my server so that it can, for example, respond to pings for any address with that prefix. If I start a TCP listening on "[::]:80", it will respond to requests to any IP address. What I want is to be able to listen on a specific IP address so that only requests addressed to that IP address will hit the server. Other ServerFault questions linked to are asking how to get a server to respond to requests to any IP address. I've already gotten that far. I want to be able to bind to any arbitrary address, but only one specific one. The problem is that Linux won't even let me start the server on a specific address if that particular address isn't statically assigned to an interface, and I'd like to work around that.



To be even more concrete, I can presently run a TCP echo server on my VPS on all interfaces:



ncat -l 2000 --keep-open --exec "/bin/cat"



Then from my laptop, I can connect to it using any random IPv6 address:



telnet 2001:19f0:6801:187:: 2000
telnet 2001:19f0:6801:187:abc:def:: 2000
telnet 2001:19f0:6801:187:abc:def:123:0 2000


This all works. If I start the server on a statically assigned address, it also works:



ncat -l 2001:19f0:6801:187:5400:ff:fe60:afc6 2000 --keep-open --exec "/bin/cat"



Now I can only connect to that particular IP address. So far so good.



Now I'd like to be able to start a server on some random address:



ncat -l 2001:19f0:6801:187:abc:123:: 2000 --keep-open --exec "/bin/cat"


But I get an error: "Ncat: bind to 2001:19f0:6801:187:abc:123:::2000: Cannot assign requested address. QUITTING." But if I ip -6 addr add dev eth0 2001:19f0:6801:187:abc:123::/64, then the previous ncat command works, and the server starts and only responds to connections to 2001:19f0:6801:187:abc:123::.




So can I configure Linux to let me start a server on any arbitrary address in my block without first adding it as a static address?



(Actually, my question is very similar to https://stackoverflow.com/questions/40198619/can-docker-automatically-add-ip-addresses-to-the-host-upon-running-container, although there they're talking about IPv4. There the answer is to statically add all addresses.)

Comments

Post a Comment

Popular posts from this blog

iLO 3 Firmware Update (HP Proliant DL380 G7)

The iLO web interface allows me to upload a .bin file ( Obtain the firmware image (.bin) file from the Online ROM Flash Component for HP Integrated Lights-Out. ) The iLO web interface redirects me to a page in the HP support website ( http://www.hp.com/go/iLO ) where I am supposed to find this .bin firmware, but no luck for me. The support website is a mess and very slow, badly categorized and generally unusable. Where can I find this .bin file? The only related link I am able to find asks me about my server operating system (what does this have to do with the iLO?!) and lets me download an .iso with no .bin file And also a related question: what is the latest iLO 3 version? (for Proliant DL380 G7, not sure if the iLO is tied to the server model)
Post a Comment
Read more

linux - How can I get my mediawiki to stop thinking I have cookies disabled?

I've searched half a day for how to resolve this issue, and can't figure it out. Shortly after I made my wiki a simple private wiki according to the instructions at Mediawiki's website, it started giving me this weird login error message: Wiki uses cookies to log in users. You have cookies disabled. Please enable them and try again. If I remove those private wiki settings, the error disappears, even if I try logging in. But I need it to be a private wiki for only my team. So what do I do? Here's what I've done so far. Just to be safe, after ever change, I try rebooting Apache using: sudo /etc/init.d/apache2 restart In my php.ini file, I have the following set: session.save_path = "/var/lib/php5" session.cookie_secure = secure session.cookie_path = /tmp session.cookie_domain = my server's internal URL (should I even set this? this field was blank before, but not commented out) session.referer_check = Off I ran the following to ensure that the fold...
Post a Comment
Read more

hp proliant - Smart Array P822 with HBA Mode?

We get an HP DL360 G8 with an Smart Array P822 controller. On that controller will come a HP StorageWorks D2700 . Does anybody know, that it is possible to run the Smart Array P822 in HBA mode? I found only information about the P410i, who can run HBA. If this is not supported, what you think about the LSI 9207-8e controller? Will this fit good in that setup? The Hardware we get is used but all original from HP. The StorageWorks has 25 x 900 GB SAS 10K disks. Because the disks are not new I would like to use only 22 for raid6, and the rest for spare (I need to see if the disk count is optimal or not for zfs). It would be nice if I'm not stick to SAS in future. As OS I would like to install debian stretch with zfs 0.71 as file system and software raid. I have see that hp has an page for debian to. I would like to use hba mode because it is recommend, that zfs know at most as possible about the disk, and I'm independent from the raid controller. For us zfs have many benefits, ...
Post a Comment
Read more