What are some alternatives?
When comparing DD-WRT and ZeroShell, you can also consider the following products
OpenWrt - OpenWrt is an open-source firmware based on Linux for wireless routers
pfSense - pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more
MikroTik RouterOS - The main product of MikroTik is a Linux-based operating system known as MikroTik RouterOS.
OPNsense - OPNsense® you next open source firewall. Free Download. High-end Security Made Easy™. Offers Intrusion Prevention, Captive Portal, Traffic Shaping and more.
IPFire - IPFire is a server distribution with intended to use as a firewall.
LibreMesh - An Open Source Sofware for Geek-free Mesh Community Networks.