# Functions for working with IP addresses

## IPv4NumToString(num)

Takes a UInt32 number. Interprets it as an IPv4 address in big endian. Returns a string containing the corresponding IPv4 address in the format A.B.C.d (dot-separated numbers in decimal form).

## IPv4StringToNum(s)

The reverse function of IPv4NumToString. If the IPv4 address has an invalid format, it returns 0.

## IPv4NumToStringClassC(num)

Similar to IPv4NumToString, but using xxx instead of the last octet.

Example:

``` sql
SELECT
    IPv4NumToStringClassC(ClientIP) AS k,
    count() AS c
FROM test.hits
GROUP BY k
ORDER BY c DESC
LIMIT 10
```

```
┌─k──────────────┬─────c─┐
│ 83.149.9.xxx   │ 26238 │
│ 217.118.81.xxx │ 26074 │
│ 213.87.129.xxx │ 25481 │
│ 83.149.8.xxx   │ 24984 │
│ 217.118.83.xxx │ 22797 │
│ 78.25.120.xxx  │ 22354 │
│ 213.87.131.xxx │ 21285 │
│ 78.25.121.xxx  │ 20887 │
│ 188.162.65.xxx │ 19694 │
│ 83.149.48.xxx  │ 17406 │
└────────────────┴───────┘
```

Since using 'xxx' is highly unusual, this may be changed in the future. We recommend that you don't rely on the exact format of this fragment.

### IPv6NumToString(x)

Accepts a FixedString(16) value containing the IPv6 address in binary format. Returns a string containing this address in text format.
IPv6-mapped IPv4 addresses are output in the format ::ffff:111.222.33.44. Examples:

``` sql
SELECT IPv6NumToString(toFixedString(unhex('2A0206B8000000000000000000000011'), 16)) AS addr
```

```
┌─addr─────────┐
│ 2a02:6b8::11 │
└──────────────┘
```

``` sql
SELECT
    IPv6NumToString(ClientIP6 AS k),
    count() AS c
FROM hits_all
WHERE EventDate = today() AND substring(ClientIP6, 1, 12) != unhex('00000000000000000000FFFF')
GROUP BY k
ORDER BY c DESC
LIMIT 10
```

```
┌─IPv6NumToString(ClientIP6)──────────────┬─────c─┐
│ 2a02:2168:aaa:bbbb::2                   │ 24695 │
│ 2a02:2698:abcd:abcd:abcd:abcd:8888:5555 │ 22408 │
│ 2a02:6b8:0:fff::ff                      │ 16389 │
│ 2a01:4f8:111:6666::2                    │ 16016 │
│ 2a02:2168:888:222::1                    │ 15896 │
│ 2a01:7e00::ffff:ffff:ffff:222           │ 14774 │
│ 2a02:8109:eee:ee:eeee:eeee:eeee:eeee    │ 14443 │
│ 2a02:810b:8888:888:8888:8888:8888:8888  │ 14345 │
│ 2a02:6b8:0:444:4444:4444:4444:4444      │ 14279 │
│ 2a01:7e00::ffff:ffff:ffff:ffff          │ 13880 │
└─────────────────────────────────────────┴───────┘
```

``` sql
SELECT
    IPv6NumToString(ClientIP6 AS k),
    count() AS c
FROM hits_all
WHERE EventDate = today()
GROUP BY k
ORDER BY c DESC
LIMIT 10
```

```
┌─IPv6NumToString(ClientIP6)─┬──────c─┐
│ ::ffff:94.26.111.111       │ 747440 │
│ ::ffff:37.143.222.4        │ 529483 │
│ ::ffff:5.166.111.99        │ 317707 │
│ ::ffff:46.38.11.77         │ 263086 │
│ ::ffff:79.105.111.111      │ 186611 │
│ ::ffff:93.92.111.88        │ 176773 │
│ ::ffff:84.53.111.33        │ 158709 │
│ ::ffff:217.118.11.22       │ 154004 │
│ ::ffff:217.118.11.33       │ 148449 │
│ ::ffff:217.118.11.44       │ 148243 │
└────────────────────────────┴────────┘
```

## IPv6StringToNum(s)

The reverse function of IPv6NumToString. If the IPv6 address has an invalid format, it returns a string of null bytes.
HEX can be uppercase or lowercase.

## IPv4ToIPv6(x)

Takes a UInt32 number. Interprets it as an IPv4 address in big endian. Returns a FixedString(16) value containing the IPv6 address in binary format. Examples:

``` sql
SELECT IPv6NumToString(IPv4ToIPv6(IPv4StringToNum('192.168.0.1'))) AS addr
```

```
┌─addr───────────────┐
│ ::ffff:192.168.0.1 │
└────────────────────┘
```

## cutIPv6(x, bitsToCutForIPv6, bitsToCutForIPv4)

Accepts a FixedString(16) value containing the IPv6 address in binary format. Returns a string containing the address of the specified number of bits removed in text format. For example:

```sql
WITH
    IPv6StringToNum('2001:0DB8:AC10:FE01:FEED:BABE:CAFE:F00D') AS ipv6,
    IPv4ToIPv6(IPv4StringToNum('192.168.0.1')) AS ipv4
SELECT
    cutIPv6(ipv6, 2, 0),
    cutIPv6(ipv4, 0, 2)

```

```
┌─cutIPv6(ipv6, 2, 0)─────────────────┬─cutIPv6(ipv4, 0, 2)─┐
│ 2001:db8:ac10:fe01:feed:babe:cafe:0 │ ::ffff:192.168.0.0  │
└─────────────────────────────────────┴─────────────────────┘
```

[Original article](https://clickhouse.yandex/docs/en/query_language/functions/ip_address_functions/) <!--hide-->