dneigh: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/sbin/dneigh - from package: dnet-progs

You may install the required package with command apt-get install {package}
Error in other languages:
dneigh: bevel nie gevind nie
dneigh: comandă negăsită
dneigh: comando não encontrado
dneigh: commande introuvable
dneigh: command not found
dneigh: käsku ei ole
dneigh: không tìm thấy lệnh
dneigh: komanda nerasta
dneigh: Kommando nicht gefunden.
dneigh: kommandot finns inte
dneigh: komut yok
dneigh: nie znaleziono polecenia
dneigh: níor aimsíodh an t-ordú
dneigh: no se encontró la orden
dneigh: no s'ha trobat l'ordre
dneigh: opdracht niet gevonden
dneigh: parancs nem található
dneigh: perintah tidak ditemukan
dneigh: príkaz nenájdený
dneigh: příkaz nenalezen
dneigh: команда не найдена
dneigh: командата не е открита
dneigh: 命令找不到
dneigh: コマンドが見つかりません