| Size | Comment |
|---|---|
| /29 | starter pack |
| /28 | usually enough |
| /27 | default allocation |
| /26 | usually enough |
| /25 | still a lot of IPs! |
| /24 | are you an organization? |
The current guideline is to allocate a /27 or smaller by default, keeping space for up to a /26 if possible. Don't allocate more than a /25 worth of addresses and please think before you allocate: If you are going to have 2-3 servers and two VPN-spaces, a /28 is enough to suit your needs. Same will go for most home-networks. This is not public internet, but our IPv4-space is valuable too! If you need a /24 or larger, please ask in the IRC chan or on the mailing list.
For example, if there is no /27 free, you can split up a /26 into two /27. If you are looking for a /27 but there are none showing in the Open Netblocks tool, instead pick one of the /26 and click Take it! When registering your inetnum, instead of writing 172.2x.xxx.0-172.2x.xxx.63 then you can write 172.2x.xxx.0-172.2x.xxx.31. This will get you a /27 and save our IP space for others.
To register for example 172.20.150.0/27, you need to fill in 172.20.150.0-172.20.150.31.
{
"prefixes": {
"29": [
"172.20.187.160_29",
"172.20.187.168_29",
"172.20.191.160_29",
"172.20.224.96_29",
"172.21.69.48_29",
"172.22.156.0_29",
"172.22.156.16_29",
"172.22.156.8_29",
"172.23.167.128_29",
"172.23.167.136_29",
"172.23.167.144_29",
"172.23.217.32_29",
"172.23.217.40_29",
"172.23.223.96_29",
"172.23.241.0_29"
],
"28": [
"172.20.132.96_28",
"172.20.133.128_28",
"172.20.167.192_28",
"172.20.167.208_28",
"172.20.2.192_28",
"172.20.2.208_28",
"172.21.69.32_28",
"172.21.90.0_28",
"172.21.90.16_28",
"172.22.129.32_28",
"172.22.148.240_28",
"172.22.149.32_28",
"172.23.120.192_28",
"172.23.179.160_28",
"172.23.216.64_28"
],
"27": [
"172.20.167.224_27",
"172.20.18.128_27",
"172.20.187.128_27",
"172.20.2.224_27",
"172.20.229.64_27",
"172.21.78.192_27",
"172.22.127.64_27",
"172.22.146.192_27",
"172.22.180.128_27",
"172.22.180.160_27",
"172.23.179.128_27",
"172.23.189.128_27",
"172.23.189.160_27",
"172.23.189.192_27",
"172.23.189.224_27"
],
"26": [
"172.20.133.64_26",
"172.20.154.0_26",
"172.20.229.0_26",
"172.21.76.64_26",
"172.22.155.128_26",
"172.22.155.192_26",
"172.23.120.128_26",
"172.23.161.128_26",
"172.23.166.0_26",
"172.23.166.128_26",
"172.23.166.64_26",
"172.23.179.0_26",
"172.23.179.64_26",
"172.23.190.0_26",
"172.23.216.0_26"
],
"25": [
"172.20.161.0_25",
"172.20.187.0_25",
"172.20.31.128_25",
"172.21.101.128_25",
"172.21.76.128_25",
"172.21.91.128_25",
"172.22.160.128_25",
"172.22.183.128_25",
"172.23.206.0_25",
"172.23.206.128_25",
"172.23.217.128_25",
"172.23.226.128_25",
"172.23.72.128_25",
"172.23.76.128_25",
"172.23.84.128_25"
],
"24": [
"172.20.226.0_24",
"172.20.3.0_24",
"172.21.126.0_24",
"172.21.127.0_24",
"172.21.92.0_24",
"172.22.104.0_24",
"172.22.151.0_24",
"172.23.115.0_24",
"172.23.133.0_24",
"172.23.169.0_24",
"172.23.188.0_24",
"172.23.204.0_24",
"172.23.213.0_24",
"172.23.214.0_24",
"172.23.65.0_24"
],
"23": [
"172.20.144.0_23",
"172.20.60.0_23",
"172.21.102.0_23",
"172.21.124.0_23",
"172.22.190.0_23",
"172.23.134.0_23",
"172.23.138.0_23",
"172.23.154.0_23",
"172.23.164.0_23",
"172.23.184.0_23",
"172.23.210.0_23",
"172.23.218.0_23",
"172.23.46.0_23",
"172.23.80.0_23"
]
},
"mtime": "2025-05-18T10:10:16Z"
}