Rebooting a Router from User Mode

學習過Cisco IOS的人都知道其實在User Mode(Router>)之下沒有什麼指令可以使用,所以通常我們也不會在User Mode停留就直接打enable進入Privilege Mode。不過我看到一篇文章分享一個bug可以讓各位在真正緊急狀況時不用進入Privilege Mode而重啟Router。

By Brian Dennis, CCIE #2210
I’m over in London this week for a CCIE Voice Bootcamp and a support engineer IMs me asking a question. He needed to remotely reload a backbone router for a new rack but for some reason the standard enable password we use for the backbone routers wasn’t working. I asked him if he could just VPN in and reload it using the power controller. He told me he was telneted into the rack using his iPhone and wanted to just do it via telnet as opposed to opening a VPN connection. For a moment I thought to myself he was just out of luck but I then remembered the old regular expression bug that would reload the router (i.e. “show ip bgp regexp ([0-9]*)(_\1)+”, “show version include ([0-9]*)(_\1)+”, etc). He types it in, the router crashes and all is good. This also reminded me that I need to update the initial configurations on Brian McGahan’s development rack (see below)

alias exec en show version include ([0-9]*)(_\1)+
alias exec ena show version include ([0-9]*)(_\1)+
alias exec enab show version include ([0-9]*)(_\1)+
alias exec enabl show version include ([0-9]*)(_\1)+
alias exec enable show version include ([0-9]*)(_\1)+
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