Error in host specification

Hello folks,

While creating a “Target” for scanning - I am using the subnet “” but I keep getting an error stating that there is an error in host specification. This is the LAN we are using! Why is it not taking it? I noticed that when the third octet is anything but a zero, it works. Please help.


I was able to fix this. Using the last octet as any other number except single digit works. I used the target as “” and it took the LAN

Had this same problem from Kali Linux. After upgrading Kali to 2019.1 we have problem with OpenVAS. Existing targets with a subnet definition (e.g. is considered invalid. Creating new targets fails, both from CLI and through GSA webinterface.

Main problem is that existing targets are no longer valid. In GSA the number op IPs is -1 for these targets. OpenVAS itself wasn’t updated.

The problem depends on the position of ‘/’. If ‘/’ is the 12th or higher character there is no problem.
So: – Fails – Fails – Fails – Fails – no problem. ‘/’ is 12th character – Fails – no problem – no problem

I’ve found a workaround for old targets that have problems after the upgrade:

  • Generate a list of all IP-adressses in the subnet for example with ‘nmap -sL’
  • Stop openvas-manager
  • Open SQLite3 databse: sqlite3 /var/lib/openvas/mgr/tasks.db
  • Update table targets. E.g. update targets set hosts = ’ where name = ‘’
  • Start openvas-manager


I can confirm this behaviour exists in a fresh and upgraded install of Kali and OpenVAS. fails with 400 error. works fine.

You could raise an issue to the development team here:

 * @brief Default maximum number of hosts a target may specify.
#define MANAGE_MAX_HOSTS 4095

 * @brief Default maximum number of hosts a user host access may specify.
#define MANAGE_USER_MAX_HOSTS 16777216

The flow of function [create_target]

                |              create_target                     |
                |        (Error in host specification)           |
                  | manage_count_hosts (clean, clean_exclude) |
                      | manage_count_hosts_max (         |
                      |    given_hosts,                  |
                      |    exclude_hosts,                |
                      |    manage_max_hosts ());         |
               |                                                       |
               |                                                       |
-----------------------------------                           -----------------------
| manage_count_hosts_max (        |                           |  manage_max_hosts() |
|     const char *given_hosts,    |                           -----------------------
|     const char *exclude_hosts,  |                                   |
|    int max_hosts)               |                                   |
-----------------------------------                  ---------------------------------------------
     |                                               | max_hosts = MANAGE_MAX_HOSTS (val: 4096)  |
     |                                               ---------------------------------------------
| gvm_hosts_new_with_max (   |
|    given_hosts,            |
|    max_hosts)              |

I find an Easy way to Solve that, you only have to put in the box of manual Target this

And it Will run Ok


NOK for me :
Example: ===> IPs = 1

LAN will not be scan :frowning:

Hi, is there any further update on this? Just installed Kali 2020.1 and OpenVas, I have the same issue with 10.x.x.x/24 subnets.

And Kali still only ships an end of life version About the Greenbone Source Edition (GSE) category


Me, too.
I’m using openvas on Debian 10 and have same issue.

For Debian 10 the same posted previously applies as well:

1 Like

Seems this has not been fixed since 2019. Anyone from the greenbone team here? - works. But only for one subnet. As soon as you have a text file with more subnets like that - it fails. “Error in host specification”

If you’re on the latest GVM-20.08 release (other GVM releases probably won’t receive much fixes anymore as they are either already EOL or will reach EOL by the end of this year) and there is something to fix the following advice is still valid because it is not guaranteed that some one of the development team is noticing that there needs to be something to fix.

Also note that AFAIK the “Error in host specification” might also happens if you’re specifying a too large netmask when creating a new target. Currently the max netmask per target is /20.

1 Like

Adding to what GvH mentioned (also, thank you, didn’t know about the -sL flag in nmap):

Also, think I had an issue with:

Running GVM 20.08 on Ubuntu 20.04, I was able to solve my hostlist CIDR subnet definition issues with:

nmap -n -sL -iL subnet_form.txt | awk ‘/Nmap scan/{gsub(/[()]/,“”,$NF); print $NF}’ > ip_list.txt

I then had no issues adding the ip_list.txt as a hostlist