---
name: "rblcheck"
section: "1"
platform: "linux"
package: "udns"
version: "0.7-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/rblcheck"
---

# rblcheck(1)

DNSBL lookup utility

## NAME

rblckeck - DNSBL lookup utility

## SYNOPSYS

**rblcheck** \[**-s** *zone*\] \[**-S** *zone-file*\] \[**-c**\] \[**-tmvq**\] \[**-n** *nsaddr*\] *address*...

## DESCRIPTION

**rblcheck** is a simple command-line to perform DNSBL (DNS-based blocklists) lookups. For every IP address (or a name, in which case it will be resolved to an address first), the utility verifies whenever it is listed in a (list of) DNS blocklists specified with **-s** or **-S** options, optionally obtains text associated with the listing (usually it is either some description about the reason of the listing or an URL referring to such a description), and displays results on standard output.

The program is implemented on top of [**udns**(3)](/udns/3.md) library.

## OPTIONS

The following options are recognized by **rblcheck**:

- **-s *zone***

  add the given *zone* DNSBL name to the list of active zones.

- **-S *zone-file***

  add list of zones from the named *zone-file* to the list of active zones (the file specifies one zone as the first word on a line, empty lines and lines starting with \`#' character are ignored).

- **-c**

  reset active zone list.

- **-v**

  be more verbose, produce more detailed output.

- **-q**

  the opposite for **-v** -- produce less detailed output.

- **-t**

  obtain text for listed addresses.

- **-n *nsaddr***

  Use the given nameserver (given as IPv4 or IPv6 address) instead of the default.  The same effect may be achieved by setting $NSCACHEIP environment variable.

- **-m**

  stop after first hit, ie after the first address which is found to be listed.

- **-h**

  print short help and exit.

If no **-s**, **-S** and **-c** options are given, **rblcheck** will try to obtain list of zones using $RBLCHECK\_ZONES environment variable, or ~/.rblcheckrc, or /etc/rblckechrc files, in that order.  If no zones are found, it will exit unsuccessefully.

## RETURN VALUE

When no addresses given are listed and no errors occurred, **rblcheck** exits with code 0.  If at least one address is listed, **rblcheck** returns 100.  In case of DNS errors, **rblcheck** returns 2.

## ENVIRONMENT

- **$RBLCHECK\_ZONES**

  if no **-s**, **-S** or **-c** option is given, **rblcheck** tries this variable to obtain list of DNSBL zones to check against.

## FILES

- $HOME/.rblcheckrc and /etc/rblcheckrc

  if no **-s**, **-S** or **-c** option is given, and no $RBLCHECK\_ZONES environment variable is set, **rblcheck** will try the two files (the first one that exists) to obtain list of DNSBL zones to check against. Each line specifies one zone (only first word in each line is used). Empty lines and lines starting with \`#' character are ignored.

## SEE ALSO

[**dnsget**(1)](/dnsget/1.md) [**resolv.conf**(5)](/resolv.conf/5.md) [**udns**(3)](/udns/3.md).

## AUTHOR

This program and manual pages are written by Michael Tokarev.