sudo apt-get install irssi

Edit the config file, ex: we are connecting to server k5.florida, chat net is zombienet, and port is 6667. You only need to change the servers entry:

sudo nano /etc/irssi.conf

Example contents:

servers = (
  { address = "k5.florida";       chatnet = "zombienet";    port = "6667"; },
);

chatnets = {
  zombienet = {
    type      = "IRC";
    max_kicks = "4";
    max_msgs  = "20";
    max_whois = "30";
  };
};

channels = (
  { name = "#lobby";     chatnet = "EsperNet";  autojoin = "No"; },
  { name = "#freenode";  chatnet = "Freenode";  autojoin = "No"; },
  { name = "#irssi";     chatnet = "Freenode";  autojoin = "No"; },
  { name = "#gamesurge"; chatnet = "GameSurge"; autojoin = "No"; },
  { name = "#irssi";     chatnet = "IRCNet";    autojoin = "No"; },
  { name = "#ircsource"; chatnet = "IRCSource"; autojoin = "No"; },
  { name = "#netfuze";   chatnet = "NetFuze";   autojoin = "No"; },
  { name = "#oftc";      chatnet = "OFTC";      autojoin = "No"; },
  { name = "silc";       chatnet = "SILC";      autojoin = "No"; }
);

aliases = {
  ATAG        = "WINDOW SERVER";
  ADDALLCHANS = "SCRIPT EXEC foreach my \\$channel (Irssi::channels()) { Irssi::command(\"CHANNEL ADD -auto \\$channel->{name} \\$channel->{server}->{tag} \\$channel->{key}\")\\;}";
  B           = "BAN";
  BACK        = "AWAY";
  BANS        = "BAN";
  BYE         = "QUIT";
  C           = "CLEAR";
  CALC        = "EXEC - if command -v bc >/dev/null 2>&1\\; then printf '%s=' '$*'\\; echo '$*' | bc -l\\; else echo bc was not found\\; fi";
  CHAT        = "DCC CHAT";
  DATE        = "TIME";
  DEHIGHLIGHT = "DEHILIGHT";
  DESCRIBE    = "ACTION";
  DHL         = "DEHILIGHT";
  EXEMPTLIST  = "MODE $C +e";
  EXIT        = "QUIT";
  GOTO        = "SCROLLBACK GOTO";
  HIGHLIGHT   = "HILIGHT";
  HL          = "HILIGHT";
  HOST        = "USERHOST";
  INVITELIST  = "MODE $C +I";
  J           = "JOIN";
  K           = "KICK";
  KB          = "KICKBAN";
  KN          = "KNOCKOUT";
  LAST        = "LASTLOG";
  LEAVE       = "PART";
  M           = "MSG";
  MUB         = "UNBAN *";
  N           = "NAMES";
  NMSG        = "^MSG";
  P           = "PART";
  Q           = "QUERY";
  RESET       = "SET -default";
  RUN         = "SCRIPT LOAD";
  SAY         = "MSG *";
  SB          = "SCROLLBACK";
  SBAR        = "STATUSBAR";
  SIGNOFF     = "QUIT";
  SV          = "MSG * Irssi $J ($V) - https://irssi.org";
  T           = "TOPIC";
  UB          = "UNBAN";
  UMODE       = "MODE $N";
  UNSET       = "SET -clear";
  W           = "WHO";
  WC          = "WINDOW CLOSE";
  WG          = "WINDOW GOTO";
  WJOIN       = "JOIN -window";
  WI          = "WHOIS";
  WII         = "WHOIS $0 $0";
  WL          = "WINDOW LIST";
  WN          = "WINDOW NEW HIDDEN";
  WQUERY      = "QUERY -window";
  WW          = "WHOWAS";
};

statusbar = {

  items = {

    barstart = "{sbstart}";
    barend   = "{sbend}";

    topicbarstart = "{topicsbstart}";
    topicbarend   = "{topicsbend}";

    time = "{sb $Z}";
    user = "{sb {sbnickmode $cumode}$N{sbmode $usermode}{sbaway $A}}";

    window       = "{sb $winref:$tag/$itemname{sbmode $M}}";
    window_empty = "{sb $winref{sbservertag $tag}}";

    prompt       = "{prompt $[.15]itemname}";
    prompt_empty = "{prompt $winname}";

    topic       = " $topic";
    topic_empty = " Irssi v$J - https://irssi.org";

    lag  = "{sb Lag: $0-}";
    act  = "{sb Act: $0-}";
    more = "-- more --";
  };

  default = {

    window = {

      disabled  = "no";
      type      = "window";
      placement = "bottom";
      position  = "1";
      visible   = "active";

      items = {
        barstart     = { priority = "100"; };
        time         = { };
        user         = { };
        window       = { };
        window_empty = { };
        lag          = { priority = "-1"; };
        act          = { priority = "10"; };
        more         = { priority = "-1";  alignment = "right"; };
        barend       = { priority = "100"; alignment = "right"; };
      };
    };

    window_inact = {

      type      = "window";
      placement = "bottom";
      position  = "1";
      visible   = "inactive";

      items = {
        barstart     = { priority = "100"; };
        window       = { };
        window_empty = { };
        more         = { priority = "-1";  alignment = "right"; };
        barend       = { priority = "100"; alignment = "right"; };
      };
    };

    prompt = {

      type      = "root";
      placement = "bottom";
      position  = "100";
      visible   = "always";

      items = {
        prompt       = { priority = "-1"; };
        prompt_empty = { priority = "-1"; };
        input        = { priority = "10"; };
      };
    };

    topic = {

      type      = "root";
      placement = "top";
      position  = "1";
      visible   = "always";

      items = {
        topicbarstart = { priority = "100"; };
        topic         = { };
        topic_empty   = { };
        topicbarend   = { priority = "100"; alignment = "right"; };
      };
    };
  };
};

Start irssi from your user account:

irssi

Example commands to connect to the “zombienet” network entered above under servers:

/NETWORK LIST
/CONNECT zombienet
/JOIN #hello
/QUIT